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Maintaining historic integrity and solving a rehabilitation dilemma: the history of hollow clay tile and an argument for its preservation

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Maintaining historic integrity and solving a rehabilitation dilemma: the history of hollow clay tile and an argument for its preservation

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Content MAINTAINING HISTORIC INTEGRITY AND SOLVING A REHABILITATION
DILEMMA:
THE HISTORY OF HOLLOW CLAY TILE AND AN ARGUMENT FOR ITS
PRESERVATION

BY

LORETTA ANN KATHRYN CIMMARUSTI

A Thesis Presented to the
FACULTY OF THE USC SCHOOL OF ARCHITECTURE
University of Southern California
In Partial Fulfillment of the
Requirement for the Degree
Master of Historic Preservation

December 2012

Copyright 2012 Loretta Ann Kathryn Cimmarusti
ii
Dedication
I dedicate this document to my family, who has always encouraged me to never give up
and continue to educate myself. To my father, who has supported me both emotionally
and financially through out my entire career; to my mother who always reminded me to
follow my passion; and finally, to my brothers who, without realizing it, have made me
the strong and courageous individual I am today. Thank you!
iii
Acknowledgements
I would like to thank, first and foremost, my committee for their dedication of both their
time and effort over the past year: Trudi Sandmeier, John Lesak, and Melvyn Green.
You’re extensive knowledge, experience and generosity during this process has always
been greatly appreciated. I would also like to thank those who provided me with essential
resources, including: David Cocke of Structural Focus, Kal Benuska of John A. Martin
and Associates, Conrad Paulson of Wiss, Janney, & Elstner, Steve Spiller of the Mission
Inn, Bruce Judd, Marcello Vavala of the Los Angeles Conservancy, and anyone else I
may have missed who provided me with much needed assistance or crucial information. I
am forever grateful.
iv
Table of Contents
DEDICATION ............................................................................................................................... II

ACKNOWLEDGEMENTS ........................................................................................................ III

LIST OF TABLES ....................................................................................................................... VI

LIST OF FIGURES ................................................................................................................... VII

ABSTRACT .................................................................................................................................. XI

INTRODUCTION .......................................................................................................................... 1

CHAPTER 1: WHAT IS HOLLOW CLAY TILE? ................................................................... 3

Material and Composition ........................................................................................................... 3

Production of Hollow Clay Tile ................................................................................................... 5

Different Types of Hollow Clay Tile ............................................................................................ 9

CHAPTER 2: THE EVOLUTION OF HOLLOW CLAY TILE ............................................ 16

Steel Skeletal Frame Building ................................................................................................... 16

The Need for Fireproof Buildings: Fireproofing Before Hollow Clay Tile .............................. 20

Original Inventors: The Great Chicago Fire and the Floor Arch ............................................ 25

Different Uses of Hollow Clay Tile in Building Construction ................................................... 31

Hollow Clay Tile Industry in the United States ......................................................................... 35

Timeline of Significant Events in the Development of HCT ...................................................... 38

CHAPTER 3: HOLLOW CLAY TILE ON THE WEST COAST ......................................... 40

Hollow Clay Tile in Southern California: Clay Deposits and Tile Manufacturers ................... 40

The Fall of Hollow Clay Tile: Earthquakes, New Building Codes and Modern Technology ... 47

CHAPTER 4: THE PRESERVATION OF HOLLOW CLAY TILE .................................... 58

Building a Case for Maintaining Integrity ................................................................................ 58

Case Study No. 1: Swan Hall at Occidental College ................................................................ 64

Case Study No. 2: The Riverside Metropolitan Museum ........................................................... 71

Case Study No. 3: The Mission Inn ........................................................................................... 77

Case Study No. 4: The Hollyhock House ................................................................................... 84

Case Study No. 5: The Ambassador Hotel ................................................................................ 90

v
CONCLUSION ............................................................................................................................ 95

BIBLIOGRAPHY ........................................................................................................................ 97

vi
List of Tables
Table 1 Chart showing sizes and weight of standard HCT blocks by the
late 1020s 36

Table 2 Timeline of significant events in the history of HCT 38

vii
List of Figures
Figure 1 Illustration depicting workers extruding HCT blocks through
a die 7

Figure 2 Photo of ruffled HCT blocks around structural steel member 12

Figure 3 Advertisement for the Los Angeles Pressed Brick Company 13

Figure 4 120 Broadway in New York after a fire showing the destruction
and damage to the wrought iron beams and cast iron columns 17

Figure 5 Photo depicts the typical design for heavy timber construction 22

Figure 6 Author’s depiction of a traditional brick arch spanning between
I-beams back filled with concrete 24

Figure 7 Author’s depiction of the type of floor arch similar to what was
Used in the Equitable Building 27

Figure 8 Author’s depiction of the type of arch used by the Pioneer Fire
Proof Construction Company 28

Figure 9 Author’s depiction of the hollow tile block floor arch with
internal webbing in multiple directions 29

Figure 10 Author’s depiction of an end construction flat arch cross section
shows internal webbing of hollow tile 30

Figure 11 Advertisement for the Hollow Building Tile Association 32

viii
Figure 12 Advertisement for the Los Angeles Pressed Brick Company 37

Figure 13 Advertisement for the Los Angeles Pressed Brick Company 41

Figure 14 Photo of original HCT blocks found in the United Artist Building
in downtown Los Angeles with Gladding McBean stamp 46

Figure 15 Damage caused by unreinforced masonry building 48

Figure 16 School in Huntington Park damaged by Long Beach earthquake 49

Figure 17 Advertisement for Gypsum Hollow Building and Partition Tile 54

Figure 18 Historic photo of Swan Hall 64

Figure 19 Original construction drawing by Myron Hunt of Swan Hall,
section, looking North and South 65

Figure 20 Photo of new ‘L’ bracket epoxied anchors, inserted into HCT
wall, ready to receive new shotcrete 68

Figure 21 Detail 5 illustrating where and how new epoxy anchors will
be attached to the existing HCT wall 69

Figure 22 Floor plan of Swan Hall 70

Figure 23 Current photo of Riverside Metropolitan Museum 71

Figure 24 Building section indicates location of HCT light well within the
attic space 72

ix
Figure 25 Partial attic plan view showing location of HCT walls in the light
well 73

Figure 26 Photograph showing the light gauge metal framing used to
reinforce the HCT walls in the light wells 74

Figure 27 Detail 11 illustrates bracing of HCT to new light gauge metal
frame 75

Figure 28 Photo showing interior bearing plate for reinforcing of the HCT
from inside of light well 75

Figure 29 Exterior shot of Mission Inn, looking towards the Rotunda Wing 77

Figure 30 Axonometric view of the Mission Inn illustrates the many wings
of the hotel and their dates of construction 78

Figure 31 Mission Inn Spanish Wing, fourth floor 79

Figure 32 Photo of original ruffled exterior HCT at the Mission Inn 81

Figure 33 Original floor plan of the Mission Inn Rotunda Wing 81

Figure 34 Photo showing the structural strengthening of the HCT buttress
at the Mission Inn 83

Figure 35 Main entrance to the Hollyhock House looking towards the
living room, pool in foreground 84

Figure 36 Original plan of the Hollyhock House 86

x
Figure 37 Photo of historic interior HCT at the Hollyhock House near the
library 87

Figure 38 Photo showing the exterior HCT terrace wall at the Hollyhock
House 88

Figure 39 Historic photo of the Ambassador Hotel 90

Figure 40 Ariel view of the Ambassador Hotel illustrates ‘H’ shape of
structure 92
xi
Abstract
This thesis is intended to be a collection of history, development, modern problems, and
solutions for the historic building material known as hollow clay tile (HCT). HCT
became commonplace in the United States after 1900, used in a number of different
building applications.
1
Following the Chicago fire of 1871, there was a demand for a
fireproofing material to protect the iron and steel framing systems of tall buildings. Terra
cotta manufacturers responded by producing a hollow block that could be wrapped
around iron and steel members to protect them from fire. This usage of the material
eventually developed into a fireproofing floor system, then evolved even further into
structural load bearing and partition wall systems.

HCT reached its peak of popularity on the west coast between the 1920s and 1940s, and
the material was used throughout Southern California, especially in areas with a large
concentration of tall buildings, like downtown Los Angeles. However, the material began
to fall out of popularity after it failed structurally in a series of earthquakes. Earthquakes
such as Santa Barbara (1925) and Long Beach (1933), both of which caused major
destruction of unreinforced masonry buildings, brought about serious changes in building
codes throughout the west coast. In addition, by the 1920s, the invention of newer, more
cost effective and easily manufactured building materials, such as Gypsum block and
fiber-board, also had a negative effect.

1
Conrad Paulson, “Structural Clay Tile,” in Twentieth Century Building Materials; History and
Conservation, ed. Thomas C. Jester. (McGraw-Hill Companies, 1995), 151.

xii

Today HCT poses a dilemma for many preservationists, architects, engineers, and
developers, especially on the west coast. HCT can be a life/safety issue, especially if the
material is located in exit corridors or escape routes. However, conservation of the
material can be crucial to the preservation integrity of the structure because it is often a
major part of the historic fabric of the building. Through case study analysis of examples
from the Southern California region, solutions for the HCT rehabilitation will be
explored.
1
Introduction
Preservationists have struggled to prove the significance of many historic building
materials and the role they play in preserving our historic resources. It is easy to identify
an aesthetically beautiful building, designed by one of the great architects of our time,
and designate it as something worth saving. It is not as easy, however, to identify a
commercial structure built originally out of common materials of its time and consider
that something worthy of preserving. Even more difficult, is attempting to justify why
those historic, original materials are worth preserving when contemporary, more efficient
materials might easily replace them.

This thesis is intended to provide a thorough history of an archaic building material
known as hollow clay tile (HCT). HCT is an earthen, masonry material composed of
what is found in common brick; however its shape and application differ greatly. HCT is
hollow, (with internal webs much like modern day concrete masonry units) unlike brick,
which is a solid unit. HCT, though not originally developed in the United States, but
refined here and used extensively throughout the construction of much of this country
around the turn-of-the-century, is considered to be a problematic historic building
material. The history of HCT in the United States is important, and the majority of its
history will be addressed throughout this document, with a focus on Southern California.

2
Not only does HCT have an extensive history as an archaic building material, it can still
be found in buildings across the country. The problems posed by HCT particularly apply
to areas where there is heavy seismic activity. In Los Angeles, various laws require older
structures to comply with building codes that make them more seismically stable, which
often times means reinforcing originally unreinforced masonry materials. Engineers and
architects struggle to determine how such materials can be reinforced and quite often,
these materials are simply removed because of the complexity and sometimes higher cost
of retrofitting them. As a result, large amounts of historic materials have been removed
from older buildings, sometimes resulting in a significant loss of integrity.

This thesis includes a number of case studies from throughout the Los Angeles area, in
which architects, engineers, and preservationists have successfully preserved HCT in
historic buildings. These case studies vary in why the material needed to be preserved,
and how the material was preserved. Although this thesis will go into great detail about
the numerous historic applications of HCT throughout its life as a building material, the
case studies touch on only a few of these application. This small collection of case studies
is designed to provide preservationists in the future with a foundation for beginning the
conversation needed when advocating for the preservation of archaic building materials,
such as HCT.
3
Chapter 1: What is Hollow Clay Tile?
Material and Composition
There are a number of different uses for and classifications of HCT and the composition
of each tile, depending on its use. Generally speaking, though, the materials that compose
HCT are more or less the same as those that make up common brick - clay and water.
However, the main difference between the content of common brick and of HCT is the
type of clay used. HCT is composed of water and one (or a mixture of) the following
three clays: shale, fire clay, or surface clay.

Fire clay falls under the category of refractory clay – which is the type of clay mined at
very deep levels and laid before the present geological era. It should be noted here that
fire clay is also used to produce firebrick, a special type of brick used to line kilns,
fireplaces and other similar structures that are required to reach extremely high
temperatures. Fire clay is the preferred type of clay for HCT due to its high level of
resistance to fire. Shale is another type of clay that is more finely grained and was
originally deposited in still water; shale was also laid before the present geological era.
Both shale clay and fire clay are used in the dense tiles (this type of block will be
mentioned in the next section), as these clays are more likely to vitrify upon firing,
creating a nearly impervious tile.
2
Finally, surface clay is a more plastic clay composed

2
To vitrify something means to make it glass-like through heat fusion.
4
of more sand than the other two clays and was laid more recently.
3
However, surface clay
is rarely used for HCT, “…due to the fact that the points of vitrification and fusion are so
near together as to render the undertaking rather hazardous – unless very even kiln
temperature is possible.”
4

The terms ‘hollow clay tile’ and ‘terra cotta tile’ have historically been used
interchangeably, which is incorrect. Terra cotta is the Italian word for “burned clay” and
has historically been linked to the production of architectural or decorative terra cotta
work. HCT and terra cotta are more or less composed of the same materials. Grog,
ground up remnants of a previously fired batch of terra cotta, when mixed with the clay
and water, help control the shrinkage during firing of the terra cotta. Grog is also used in
the production of dense tiles.
5
Terra cotta and HCT are two completely separate building
materials, and although they are composed of similar components, their functions as
building materials are very different.

3
Specification on hollow tile standards and compositions in: The Hollow Building Tile Association,
Handbook of Hollow Building Tile Construction, Chicago: The Hollow Building Tile Association, 4.

4
Roy H. Minton, E. M., “Notes on a New Style of Hollow Building Block,” Brick and Clay Record,
September 1905, 86.

5
Jeremy C. Wells, “History of Structural Hollow Clay Tile in the United States,” Construction History 22
(2007), 32. There is no definitive answer on whether grog is a component of any other types of HCT.
5

Production of Hollow Clay Tile
Although manufacturing methods of HCT throughout the United States may vary
depending on manufacturer, this section will focus on the general process of
manufacturing HCT blocks during the peak of the material’s production. Clay deposits
are found throughout the United States and manufacturing facilities were historically
located close to clay deposits to speed up production of HCT blocks.
The invention of brick-making machines during the latter part of the 19
th
century
had a revolutionary effect upon the structural clay products industry, since these
machines made possible the manufacture of hollow units of sizes and shapes that
could not be produced commercially by hand.
6

The following explanation of how HCT blocks are produced is adapted from Harry C.
Plummer’s book titled Brick and Tile Engineering; Handbook of Design.
7
Generally, the
production method consists of selection, storage, preparation, mixing, shaping, drying,
and burning. First the clay is selected depending on the type of HCT being manufactured.
This process is often referred to as ‘winning’ the clay. Usually, surface clays can be dug
out of the earth, but for deeper clays such as shale and fire clay, it must be blasted out.
Next, depending on whether the clay has been stored as part of transportation or it comes
straight off the conveyer belt, it is then moved to a machine where the clay is prepared.

6
Harry C. Plummer, Brick and Tile Engineering; Handbook of Design, (Washington, DC: Structural Clay
Products Institute, 1950), 13.

7
Ibid. This book is a good resource for detailed information of the material composition of HCT, its many
applications in construction, and how the different types of HCT used.
6
This machine is known as the granulator, which breaks up the large pieces of clay. The
clay is then ground into a fine matter that can easily be mixed to create a smooth, clean,
mud-like end product.

Mixing and tamping of the clay happens after it has been thoroughly prepared. Water and
other additives are mixed with the clay at this point in a pug mill – a machine with
revolving thin blades that thoroughly mixes the matter.
8
The point of this stage is to make
the clay into a mixture that can easily be formed into the desired shape and then cut.
The manufacture of HCT is done by a method known as the ‘stiff mud method’.
In order for a block to be manufactured in this way, it must have moisture content
between 12 and 15 percent because the clay is extruded through a die as opposed
to being formed by a mold.
9

At this point, the clay mixture is extruded through a die in the appropriate shape (see
Figure 1). Once the clay exits the die, it is then cut and the block (which is larger then the
desired size to allow for shrinkage) is moved to the drying room.

8
Also during this time, the clay sometimes goes through a ‘de-airing’ process. De-airing can help
strengthen the clay and increase the usage of the lower-grade clays. To do this, the clay passes through a
vacuum of mercury before it enters the pug mill.

9
Plummer, Brick and Tile Engineering, 14.
7

Before the firing of the newly formed blocks, the clay must dry. Most of the moisture
must be removed during this time.
Moisture occurs in clay ware in three forms: Free water which fills the pore
spaces; water which clings to the pore walls after the free water is removed; and
hygroscopic, colloidal, and chemically combined water.
10

The heat and moisture levels inside of the drier must be monitored at all times in order to
avoid ruining the blocks. The final and most important step in the process is firing. Firing
of the block is done in a kiln and various types of kilns are used: scove, muffle,
continuous, periodic up-draft, periodic down-draft, and tunnel kiln. The scove kilns were

10
Ibid., 18.
Figure 1: Illustration depicting workers extruding HCT blocks
through a die. Source: Pioneer Fire-Proof Construction Company,
Patentees, Manufacturers, and Contractors, Every Description of
Hollow, Solid and Porous Tile for Fire-Proofing Buildings,
Chicago: June 1888, 10.
8
historically used most often for HCT and have proven to be the most efficient kilns for
firing. The scove kiln works by stacking the unburned blocks in arches so that when the
blocks are fired, the gas can move through and around the blocks. The outside of these
arches are covered with soft-burned bricks and filled with plaster so that no heat escapes
the kiln. The entire firing process can take up to 100 hours. The first twelve hours is
dedicated to the water smoking stage where the last bit of water in the blocks is removed.

After the water smoking stage there is a transition period of roughly ten hours, followed
by the dehydration period. During this period, the kiln reaches approximately 1300
degrees Fahrenheit. The dehydration and the oxidation period overlap for about fifteen
hours, with the oxidation period lasting roughly 21 hours. Once the oxidation period is
reached, the heat inside of the kilns rises more slowly - this is known as temperature
maturing and lasts for about twenty hours. Finally, vitrification occurs when the highest
heat is reached (approximately 1800 – 2200 degrees Fahrenheit) and lasts 30 hours.
Glazing happens during the vitrification process by adding salt and other chemicals to the
fire. “The vapors from the salt are carried into the kiln, where the sodium comes in
contact with the surfaces of the ware and combines with the silica and alumina of the clay
body to form a coating.”
11
Salt-glazing, as this is known, is the most common type of
glazing for HCT.

11
Ibid., 20.
9
Different Types of Hollow Clay Tile
HCT was either used for fireproofing (non load-bearing) or for structural purposes (load-
bearing). By the late 1920s, the United States Department of Commerce; Bureau of
Standards issued master specifications (#507 & #508) for HCT. According to these
standards, HCT was “tile, hollow, clay, load-bearing wall” tile, or
“tile, hollow, clay, fireproofing, partition, and furring” tile.
12
The term ‘master
specification’ will be used when referring to the United States Department of Commerce
issued standards.

HCTs are separated into categories depending on the ‘grade’ of tile. This refers to the
tile’s characteristics, which includes water absorption, strength, fire resistance, etc.
Numbers of categories for each grade of tile differ depending on manufacturer, but
typically, the grades are separated into four general categories - dense, porous, semi-
porous, and glazed.

Dense tiles (sometimes referred to as non-porous tiles) are composed solely of clay, grog
and water - the clay usually being fire clay or shale clay.
Compared with other clays, fire clay contained a low percentage of metallic
oxides (from 9.25 to 1.39 percent) and a high percentage of silica (70 per cent or

12
Department of Commerce; Bureau of Standards, Circular of the Bureau of Standards, U.S. Government
Master Specification Tiles, Hollow, Clay, Load-bearing Wall, No. 507, August 10, 1927 and Department of
Commerce; Bureau of Standards, Circular of the Bureau of Standards, U.S. Government Master
Specification Tiles, Hollow, Clay, Fireproofing, Partition, and Furring, No. 508, August 10, 1927.

10
more). Fire clay also had a lower ‘softening points,’ or the point at which the clay
particles begin to fuse. The end result was more complete vitrification than with
other clays.
13

Dense tiles are typically structural tiles and must not be able to absorb less than eight
percent water (for vitreous tiles) or twelve percent (for hard burned tiles).
14
Dense tiles
are typically used for structural purposes: foundations, exterior walls or columns and are
fired the longest, making them the strongest of all the tiles. Though also considered
fireproof, these types of tiles are not used solely as fireproofing as they often times crack
under high temperatures.
15
In a 1903 article from Fireproof Magazine, dense tiles are
recommended for use in “grain elevators, grain bins, breweries, and cold storage plants”
because dense tiles are structurally the strongest.
16

Porous tiles are typically used in fireproof interior partition walls. Porous tiles are
composed of combination of clay, water, and sawdust or other combustible materials.
When the tile is fired, sawdust burns out of the tiles leaving hollow cells within the tile,

13
Wells, “History of Structural Hollow Clay Tile,” 34.

14
The Hollow Building Tile Association, Handbook, 5.

15
Glazed tiles, which will be addressed shortly, could fall under this category as well because the glaze
creates a vitreous surface.

16
E. A. Hoeppner, “Modern Fireproofing,” Fireproof Magazine, April 1903, 26.
11
which is what makes this tile highly resistant to fire.
17
Porous tiles can easily be nailed
into, making these tiles especially good for interior walls. Sometimes this type of tile was
referred to as ‘terra cotta lumber’ specifically for this reason. However, the composition
of ‘terra cotta lumber’ is different from that of real terra cotta – there is no grog added to
this type of tile. Structurally, these tiles are the weakest of all because of the
incorporation of the sawdust, which as mentioned before, makes the tiles more porous
and therefore less structurally stable.

Semi-porous tiles, or sometimes referred to as “ordinary” tiles, are the most common type
of HCT and were the tile of choice for fireproofing. Semi-porous tiles are composed of
clay, water, and an extremely fine combustible material like coal. The fine material burns
out during the firing process leaving these tiles slightly less porous than porous tiles.
Semi-porous tiles are “best described as a tile having an absorption value greater than
twelve per cent, but otherwise reasonably hard burned, dense or semi-porous in
structure.”
18
Because these tiles could be used internally for partition walls or externally
for infill, they were usually ruffled around the outside edge, which allowed the stucco or
plaster to stick better (see Figure 2). Semi-porous and porous tiles are not suitable for
areas exposed to the elements. Because of their porous nature and the ability to absorb a

17
The hollow cells within the body of these tiles allow the tiles to be more porous and therefore absorb
more water, making them more fire resistant then the extremely dense tiles.

18
The Hollow Building Tile Association, Handbook, 5.
12
fairly large amount of water, these tiles readily fall victim to freeze/thaw cycles.
19
Semi-
porous tiles can be recommended for exterior use, but only when they are finished with a
protective coating like finish brick or stucco.

Glazed tiles, or specifically salt glazed tiles, can vary in body composition and have a
glazed finish on the outside of the tile. Glazed tiles are used in situations where the tile is
exposed to extreme conditions, for example, as sewer pipes. To create the glaze, a certain
amount of salt is added to the kiln during the firing process, producing a glass like finish
on all exterior surfaces of the tile. Glazed tiles could also be used as decoration; the

19
Freeze/thaw cycles are only a problem in areas where temperatures drop below freezing. When water is
trapped within the tiles and freeze, then thaw, it causes major expansion and contraction within the tile,
therefore causing the tiles to break and fail.
Figure 2: Photo of ruffled HCT blocks around structural
steel member. Source: photo by author.
13
glazed finishes resemble non HCT decorative glazed tiles and could be used to finish
both interior and exterior walls.

In Structural Clay Tile, author Conrad Paulson, from the book “Twentieth Century
Building Materials,” addresses each type of application for HCT and separates them into
three different categories: floor, load-bearing and shear. The first category is for the use
of HCT as floor arches. These tiles have a specific shape due to the arch system and were
generally composed of interlocking, hard burned (dense) tiles. Second are load-bearing
tiles like those tile used in bearing walls (exterior walls) or foundations. Because load-
bearing tiles must have the ability to carry a designated load, they are also dense tiles.
The final category is reserved for shear walls. Partition wall tiles fall in this category. The
reason for this is because the fireproof partition walls acted as shear in skeletal frame
Figure 3: Advertisement for the Los Angeles Pressed Brick Company. Source:
Southwest Building and Contractor, vol. 55, no. 2 (1920), 18.
14
construction. These tiles are typically of the semi-porous tile type because they must have
great fireproofing qualities, but have little structural stability (semi-porous tiles are more
fragile). Sometimes, porous tiles were used in combination with semi-porous tile in
partition walls because porous tiles would be placed where finish materials, such as
molding, needed to be nailed down.

The strength, size and application of each HCT block shape depend on whether it is used
for end or side construction.
20
However, the terms ‘end construction’ and ‘side
construction’ are only used in floor arches, exterior walls or foundations. Partition walls
use a completely different size tile laid in the manner similar to that of end construction.
This is another important distinction given to blocks of HCT and its application in the
construction of buildings.

Structural tiles, as mentioned before, are typically less porous and denser, making them
physically stronger. In a stand alone structure, where tiles are laid with the internal voids
align vertically, the webbing creates an integrated structure that allows the weight of the
material to travel down the path of the tile wall and into the foundation. In some case, the
voids could be filled with mortar. The same condition is created when the blocks are laid
with the voids going horizontally, except that it is not possible to fill the voids with
mortar in this orientation. However, once this system is inserted into a frame (as in a

20
End construction implies blocks are stacked with the internal voids of the tiles running vertical within the
wall. Side construction implies the blocks are stack with the internal voids running perpendicular to each
other.
15
partition wall), where the wall system of HCT is no longer acting independently but
becomes dependent on the action of another structure (a moment frame), the internal
voids become weak when the HCT wall system moves (in an earthquake when there is
lateral movement). HCT becomes characteristically weak and brittle under the external
force of the moment frame – this is when the tile shatters and breaks away causing a wall
failure.

16
Chapter 2: The Evolution of Hollow Clay Tile
Steel Skeletal Frame Building
To understand the evolution of HCT in building construction, it must first be understood
that the use of HCT came about as a result of the development of the steel skeletal frame
and the demand for fireproof buildings. Prior to the development of the steel skeletal
frame building, which revolutionized the building industry in many ways, the masonry
load-bearing system was the most common system used in multi-story buildings. The
masonry load-bearing system is a compression based system, meaning a structural wall
stands up because the weight of the building material transfers down through the wall and
into the ground.
In masonry load-bearing structures, the wall carries the weight of the entire
building; floor beams and the weight of each floor are supported by the load-
bearing walls. Therefore, the thickness of the wall must increase in direct
proportion to the building’s height.
21

As masonry buildings got taller, the ground floor walls were extremely thick, resulting in
very little open space on lower floors, a challenge for highly dense urban areas where
increasing population resulted in a need for more usable space.
22

21
Susan Tunick, “The Evolution of Terra Cotta: Glazing New Trails,” APT Bulletin 32, no 4 (2001), 3.

22
Rent was typically much higher on the lower floors of multi-story building because the unreliability of
the newly developed elevator made upper floors less attractive. As the elevator become more efficient,
upper floor space became more popular.
17
Between 1850 and the early 1900s, with the advances in the metal technology, structural
systems for tall buildings changed drastically. A new hybrid system of cast iron beams in
combination with the masonry load-bearing system and wrought iron became the norm.
23

Cast iron production requires little precision and was easy to manufacture. It contains a
high quantity of carbon (approximately four percent), which makes cast iron brittle.
Wrought iron contains almost no carbon and is therefore very ductile and capable of
carrying tension loads. Cast iron members would be combined with wrought iron
members in the construction of many buildings in the second half of the nineteenth
century. However, both are weakened by heat and fire (see Figure 4). Designers utilized
cast iron for the compression members and wrought iron for tension members in trusses

23
Louis, “Hollow Tile Floor Construction,” 300.
Figure 4: 120 Broadway in New York after a fire showing the
destruction and damage to the wrought iron beams and cast iron
columns. Source: Historical Building Construction: Design,
Materials & Technology, 2
nd
ed. by Donald Friedman (New
York: W. W. Norton & Company, 2010), 28.
18
for roof structures, etc.
24
Wrought iron did not carry heavy loads in compression and cast
iron proved to be insufficient against lateral loads: “… the flexural stress in columns
caused by wind loads can exceed the compressive stress caused by gravity loads. Cast
iron in tension fails in a brittle unpredictable manner.”
25

The development of iron beams and columns led to the development of another metal.
Steel, which is stronger than iron and can carry heavier loads yet still use roughly the
same amount of material, began to replace the weaker materials, like iron. Steel performs
well in both tension and compression allowing it to resist both lateral and gravity loads
without the use of a secondary structure. Unlike cast iron, steel structures were not reliant
on masonry load-bearing system. The steel skeletal frame system became the most
common structural system for buildings over three stories tall.

During this period, other hybrid structures that combined steel with partial masonry load-
bearing systems were also developed. These systems included various combinations: iron
floor beams supported by load-bearing exterior walls in combination with iron columns
(bearing system); exterior walls supported independently from the interior skeletal frame
(cage frame system); and structures built completely out of iron or steel which supported

24
J. Stanley Rabun, Structural Analysis of Historic Buildings, (New York: John Wiley and Sons, Inc,
2000), 163.

25
Donald Friedman, Historical Building Construction: Design, Materials & Technology, 2
nd
ed. (New
York: W. W. Norton & Company, 2010), 58.
19
exterior curtain walls (skeletal system).
26
However, for the purposes of this paper, the
focus will be on the self-supporting steel skeletal frame structure.

During the development of the tall building, architects understood buildings needed to
resist against both gravity and wind. Resistance against lateral loads and shear stress were
usually not taken into consideration.
27
Consequently, bearing and cage frame systems did
little to protect against lateral loads. The benefit of the steel skeletal frame building was
that the overall structure could act independently from any interior or exterior wall; the
collapse of one of those walls would not jeopardize the integrity of the entire building.
This was extremely important because at this time, masonry was still the primary material
used to construct interior and exterior walls. Without knowing it, by infilling skeletal
frame walls with brick, as was the typical way of building skeletal frame systems at this
time, the brick acted as shear and helped protect the skeletal frame against lateral loads.
However, brick used independently as a load-bearing wall does not resist against lateral
loads. The infilling of steel skeletal frame walls plays an important role in the increase in
popularity of HCT.

One drawback of the steel skeletal frame building is that unlike masonry, steel is not fire
resistant. Steel, when exposed to temperatures greater than 1,000 degrees Fahrenheit,

26
Ibid., 57.

27
Lateral loads and shear stress are both loads that act horizontally on a structure, such as loads caused by
earthquakes. Lateral load resistance - in terms of how structures function – is important in understanding
the vulnerability of hollow clay tile.
20
weakens and may cause collapse under heavy loads. Also, “Iron and steel are extremely
vulnerable to ‘cold water shock’ when they are subjected to water by firefighters during a
fire when they are at these elevated temperatures.”
28
Once the steel skeletal frame
building grew in popularity, architects needed to find a way to fireproof their buildings.

The Need for Fireproof Buildings: Fireproofing Before Hollow Clay Tile
Thinking man has always preferred to house himself and his possessions in
buildings of fireproof construction. This preference has been due to the first law
of mankind, which is self-preservation, and second, to the economies and peace of
mind resulting from the protection of his possessions.
29

Among the forces that buildings are designed to protect against, fire is one of them. As
buildings around the turn of the century got bigger and taller, more people could occupy
their interior spaces and protecting occupants from internal and external fires was
becoming increasingly challenging. Historically, buildings were built out of wood, which
has a very low resistance to fire. Even in some of the more developed structural systems
like the cage frame and bearing systems, floor joists were built out of wood because they
are lightweight and strong. Wood is abundant throughout the United States and to this
day, is still the most common building material for basic construction.

28
F. E. Kidder, “The Architect’s and Builder’s Pocket-book,” 13
th
ed. (New York: John Wiley and Sons;
London: Chapman & Hall: 1902). Quoted in J. Stanley Rabun, Structural Analysis of Historic Buildings,
(New York: John Wiley and Sons, Inc, 2000), 220.

29
Louis, “Hollow Tile Floor Construction,” 299.
21
Slow-burning construction (late nineteenth century, early twentieth) was the first major
attempt at consciously constructing buildings to be fireproof. “The term mill construction
as used in the late nineteenth century and early twentieth century usually referred to a
type of construction that utilized heavy timber girders, beams, and columns as framing
inside load-bearing masonry walls.”
30
Typically in slow-burning construction, “the frame
and floor consisted of wood (or cast iron) posts, large dimension girders, and plank
floors.”
31
When slow-burning construction was used, interior spaces were
compartmentalized and each space fireproofed to protect the spread of fire throughout the
building. The concept was that each room, or “compartment” would burn slowly enough
that the fire could be put out quickly using fire-fighting equipment that was kept on
hand.
32
The flooring system consisted of heavy girders typically spaced eight to ten feet
apart that were decked with wood planks. Fire resistance resulted from a combination of
the heavy girders, the waterproofing paper and finish flooring applied to the deck planks.
Slow-burning construction became an acceptable style of fireproofing. Insurance
companies required builders to use slow-burning construction in order for them to insure
the structure.

30
Rabun, Structural Analysis of Historic Buildings, 137.

31
Sara E. Wermeil. “Heavy Timber Construction in Late-Nineteenth Century Commercial and Industrial
Buildings,” APT Bulletin 35, no 1 (2004), 56.

32
Sara E. Wermiel, The Fireproof Building; Technology and Public Safety in the Nineteenth-Century
American City (London: The John Hopkins University Press, 2000), 105.
22

Slow-burning construction was most typically used for mill construction or large
warehouse type structures (see Figure 5).
Textile mills of the 1870s – 90s were three stories to four stories, as required by
the factory process. Later mill buildings were single-story factory structures with
trussed roofs and large open areas. Vibrations and heavy machinery made the
optimum mill building design a single-story structure with long spans and open
spaces for machinery and process.
33

However, the system was commonly replicated in multi-story wood framed buildings as
it proved to be effective for fireproofing factories.

33
Rabun, Structural Analysis of Historic Buildings, 137.
Figure 5: Photo depicts the typical design for heavy timber construction. Source:
Historical Building Construction: Design, Materials & Technology, 2
nd
ed. by
Donald Friedman (New York: W. W. Norton & Company, 2010), 20.
23
As early as 1897, Peter B. Wight, who undoubtedly learned about this system through the
pages of American Architects and Builder News (AABN), brought it to the attention of
New York insurance agents in a paper he read at a meeting.
34
However, slow-burning
construction proved to be inadequate for multi-story commercial structures. The system,
originally designed to carry much less weight than what was required for a commercial
type structure, failed in numerous fires leading to this style of fireproofing to fall out of
popularity.
35

Other systems for fireproofing commercial high-rise structures were being developed by
architects to protect buildings from the spread of fire. It is easier to contain a fire within a
structure if you can minimize its spread to other floors or rooms. With masonry buildings
it seemed natural to begin to solve this problem in interiors by fireproofing floors (as
exteriors were more fire resistant if they were clad in resistive materials such as masonry,
which was very common at the time.)

34
Peter B. Wight would later be known for his contributions to the development of HCT used as
fireproofing. Wermiel, The Fireproof Building, 119.

35
Wermiel, The Fireproof Building, 123-128.
24
Initial attempts at creating fireproof floors included the use of brick floor arches spanning
between structural iron beams. The brick floor arch system was perfected in Great Britain
and became popular in the United States by the 1850s. This type of floor construction
was used in the State House Row in Philadelphia, constructed around 1813.
36
Brick floor
arches became so successful that by the mid 19
th
century, the federal government
required its use in the construction of all future federal buildings (see Figure 6).
37

However, the solid brick arch was extremely heavy; which did not solve the problem of
decreasing the load of multi-story buildings constructed out of iron and steel as opposed
to masonry. Also the brick arch took up large amounts of space. Large quantities of
mortar and concrete were required to make floors and ceilings flat again where brick
arches were employed. Other systems for floor fireproofing were also tested during this
period; concrete arches similar in design to that of the brick floor arch, and the corrugated
iron and concrete arch. However, none of these systems were lightweight.

36
Louis, “Hollow Tile Floor Construction,” 300. The use of the floor arch in this building is one of the
earliest examples of the brick floor arch used in the United States.

37
Wermiel, The Fireproof Building, 73.
Figure 6: Author's depiction of a traditional brick arch spanning between I-beams, back-filled with
concrete.
25
Original Inventors: The Great Chicago Fire and the Floor Arch
The Great Chicago Fire of 1871 was a turning point for fireproofing steel skeletal frame
buildings. Considered to be one of the most costly fires in American history, the Chicago
fire caused damage to hundreds of structures throughout the city. A drought left Chicago
without enough water to put out the fire quickly, which in turn left structures burning for
hours. The majority of the structures that burned in the Chicago fire were of wood-frame
construction – proving that wood structures are extremely difficult to protect against fire
damage. Though many buildings were considered fireproof at that time, the duration of
time those buildings burnt lead to the failure of their fireproofing systems. At the annual
American Institute of Architects, convention, the fire in Chicago was the topic on
everyone’s mind. Peter B. Wight, who by this time had become somewhat of an expert on
fireproofing, blamed the collapse of so many fireproof buildings on the failure of the cast
iron columns. He also noted sag where beam flanges were exposed to fire and that such
structural members needed to be protected from both fire and heat.
38

In this seeming afterthought, Wight articulated a key idea: he realized, although
tentatively at this point, that to survive a fire, buildings could not be merely
noncombustible, but also had to resist the effects of heat. The next phase of
fireproof construction technology developed from this insight.
39

The Great Chicago Fire of 1871 resulted in high demand for a better fireproof building.

38
Wermiel, The Fireproof Building, 82.

39
Ibid.
26
There is much discussion around exactly who invented the hollow tile floor arch, as there
were a few architects at that time that had implemented similar systems in their buildings.
The floor system was inspired by a technique that had been in use for hundreds of years
in cities and cultures throughout Europe. Romans used objects like clay pots and hollow
bricks to lighten the weight when creating vaults.
40
Also, the French set clay pots in
plaster in a similar manner to the Romans. The English copied this design as well – “arch
pots” were produced in England by the late 18
th
century.
41
Eventually, this design
evolved into a floor arch system that would then be adopted and modified by American
architects to what we now know as the hollow tile floor arch.

Numerous sources claim that Fredrick A. Peterson, the architect for the Cooper Institute
in New York was the first to experiment with hollow tile floor arches between steel I-
beams.
42
Peterson’s hollow tiles were made of fire clay and molded by hand. Peterson
took out a patent on his design of the hollow tiles for the Cooper Institute in 1855.
However, Peterson’s tile did not gain popularity as it was heavy and the large size made
it difficult to span long distances. In 1871, Balthaser Kriescher (a manufacturer of fire
brick from New York) patented his hollow tile and designed a flat-arch system using his
hollow tiles. In Kriescher’s invention, the hollow tile adjacent to the iron beam was

40
Jeremy C. Wells, “History of Structural Hollow Clay Tile in the United States,” Construction History 22
(2007), 28.

41
Wermiel, The Fireproof Building, 85.

42
The Cooper Institute in now known as the Cooper Union Building.
27
molded with a flange that reached down below the beam flange encasing it in the hollow
tile. This system helped protect the beam flange against fire.
43

After the 1871 fire in Chicago, many local architects and builders knew there would be a
high demand for fireproof construction and saw Chicago as the place to introduce this
fireproofing system. Another hollow tile floor arch system inventor, George H. Johnson,
first employed the system in the Kendall Building, now known as the Equitable Building
(see Figure 7). In the Kendall Building, the arch was flat on both the top and the bottom.
Johnson also employed hollow tile wall partitions in his design for fireproofing of the
Kendall Building. Johnson employed a slightly different style arch in Chicago City Hall.
These arches were curved on the top and flat on the bottom. Eventually, the curved style
of floor arch would fall out of popularity.
44

George H. Johnson proved to be more of a savvy businessman than some of the other
innovators in the field of fireproof construction and in 1880 created the Pioneer Fire-
Proof Construction Company based out of Chicago. Pioneer, as it became known, would

43
Wight, “Origin and History of Hollow Tile Fire-Proof Floor Construction,” 53. The resource is a good
source for information about the initial designs for hollow tile floor arches.

44
Information regarding original inventors of the hollow tile for arch can be found in: Louis, “Hollow Tile
Floor Construction,” 301.
Figure 7: Author's depiction of the type of floor arch similar to what was used in the Kendall Building.
28
eventually become one of the most well-known and respected construction and
manufacturing companies of HCT in the United States (see Figure 8).

Before 1883, all HCTs used in the floor arch system had either no internal webbing or
webbing in only one direction. Over time, architects began to realize these tiles were
weaker than they needed to be. The use of internal webbing in HCT is important because
it helps strengthen the structure of the tiles. The Mutual Life Insurance Company of New
York building is one of the first buildings to use HCT with internal webbing.
In 1883, the contract for the floor in the new building for the Mutual Life
Insurance Company of New York was awarded to a Chicago fire-proofing
contractor. This arch consisted of a 9-inch tile, each tile with one vertical and one
horizontal web.
45

The style of tile used in the Mutual Life Insurance Company is similar to what all HCT
would eventually look like – internal webbing in both directions (see Figure 9).

45
Ibid.
Figure 8: Author's depiction of the type of arch used by the Pioneer Fireproof Construction Company.
29

Tile composition up until this point was also slightly different. Previously, the
composition of HCT was more closely related to brick and with an occasional inclusion
of fire clay.
46
In 1881, the Montauk Building in Chicago, designed by D. H. Burnham,
and fireproofed by Peter B. Wight, employed HCT in floor arches made solely out of
fire-clay.
47
This type of tile is more closely related to the HCT we know of today which is
made of either fire clay, shale, or surface clay – or a mixture of the three.

During the later part of the 19
th
century, there were two main types of systems being used
for the construction of floor arches: the side-pressure arch or side construction, and the
end-pressure arch or end construction. In side construction, the voids in the tiles run
parallel to the floor beam. In end construction, the voids are perpendicular to the floor
beam. The end construction system came a bit later in terms of design of the arch system,

46
Wells, “History of Structural Hollow Clay Tile in the United States,” 30.

47
Louis, “Hollow Tile Floor Construction,” 301.

Figure 9: Author's depiction of hollow tile block floor arch with internal webbing in
multiple directions.
30
but proved to have more advantages over the side construction.
48
Not only was the end
construction arch able to carry more weight, the skew-backs (the tile adjacent to the floor
beam) could be cut more easily from one piece of hollow clay tile (see Figure 10).
49

Eventually, a combination of both systems proved to be the most efficient. In the
combination system, end construction is used in the entire arch except where the keystone
is inserted. The keystone is laid in the side construction pattern.
50

The increase in popularity of HCT grew in direct proportion to the development of the
clay products industry of the United States. By the mid 19
th
century, architectural terra
cotta was used as a replacement for the more expensive stone cladding materials.
Architectural terra cotta was easy to manufacture and the abundance of clay deposits

48
Wells, “History of Structural Hollow Clay Tile in the United States,” 30.

49
Louis, “Hollow Tile Floor Construction,” 302.

50
Conrad Paulson. “Structural Clay Tile,” in Twentieth Century Building Materials; History and
Conservation, ed. Thomas C. Jester, (McGraw-Hill Companies, 1995), 152.
Figure 10: Author's depiction of an end construction flat arch. Cross section shows
internal webbing of hollow tile.
31
throughout most of the United States allowed for the growth of the industry. The clay
products industry created a foundation of skilled craftsman and manufacturers upon
which the production of HCT grew.

The advantage of the use of HCT over other fireproof materials was its low cost to both
manufacture and construct. In comparison to brick, HCT blocks were larger in size and
less expensive to produce. According to J. J. Cosgrove in the book Hollow Tile
Construction, the amount of tile needed for a HCT house was far less then the amount of
tile needed for a brick house. For a 3x12x12 block for a wall partitions, a HCT residence
only needed 240-250 blocks, where as a brick wall of equivalent size needed 1440-1500
bricks.
51
Additionally, construction of HCT floor arches and walls was fairly easy and
could be undertaken by a layman.

Different Uses of Hollow Clay Tile in Building Construction
The use of HCT in floor arch systems was successful as a fireproofing material,
eventually leading to its wider use throughout buildings, in wall systems and foundations.
As a fireproofing material, non load-bearing HCT was used to wrap structural members
like steel or wood columns and as is already known, in floor arches to fireproof between
floors. Those systems eventually lead to the use of HCT in wall partitions, as an infill
material between steel and concrete columns.

51
J.J. Cosgrove, Hollow Tile Construction (New York: U.P.C. Book Company, 1921), 159 (see chart).
32
Load-bearing tile, also known as structural tile, has a composition slightly different than
that of fireproofing tile. Load-bearing tile can be used in the construction of free standing
exterior walls, roofs, foundations and even columns in single story buildings.
52
Both
types of tile were advertised not only as fireproof, but vermin and water resistant,
lightweight, and easy to build with.

It is unclear exactly when and how the use of HCT evolved from the floor arch system to
use as a structural building material. By the late 19
th
century, the Pioneer Fire-Proof

52
Conrad Paulson, “Structural Clay Tile,” in Twentieth Century Building Materials; History and
Conservation, ed. Thomas C. Jester, (McGraw-Hill Companies, 1995), 152.

Figure 11: Advertisement for the Hollow Building Tile
Association. Source: Architectural Forum, vol 35, issue
1, 10.
33
Construction Company was already advertising that their HCT could be used not only for
fireproof floor arches but also for bearing walls and construction of entire structures.
53

According to the Pioneer Fire-Proof Construction Company’s 1888 catalog for their
fireproof tile,
Brick arches and concrete average 75 pounds per square foot: corrugated iron and
concrete arches about the same. The hollow tile arch will average with concrete
but 35 pounds per square foot, thus affording a saving in the surplus weight of the
material of 40 pounds upon each superficial foot of floor surface.
54

During this time though, only a handful of manufacturers specialized in and produced
HCT each with its own formula and composition/process. When government standards
for HCT were developed in the early 1920s, it helped streamline the production and use
of HCT as a building material.

The use of HCT was also made extremely popular by its use in silos and grain elevators.
One of the first grain elevators constructed of HCT was the North Start Malting
Company’s plant in Minneapolis, Minnesota, built by the St. Anthony Elevator
Company.
55
Fireproof construction had become very popular by this time and architects
were beginning to understand how such a remarkable building product could be used in a

53
The Hollow Building Tile Association, Handbook of Hollow Building Tile Construction, (Chicago: The
Hollow Building Tile Association, 1921), 25.

54
Pioneer Fire-Proof Construction Company. Patentees, Manufacturers, and Contractors, Every
Description of Hollow, Solid and Porous Tile for Fire-Proofing Buildings. (Chicago: June 1888), 15.

55
E. V. Johnson, “Fireproof Tile Grain Elevator,” Fireproof Magazine, July 1902, 29.
34
number of different ways. According to a 1902 article in Fireproof Magazine by E. V.
Johnson, grain elevators were especially susceptible to fire therefore carried heavy fire
insurance rates. The most obviously solution to better fireproofing was to build such
grain elevators out of HCT, a material that had proven itself as fireproof.

Grain elevators were often times constructed in the middle of densely populated cities.
They usually consisted of multiple elevators, constructed close together and clustered in
one central area. The North Star Malting Company’s plant consisted of “twelve tile tanks
or bins, erected in two rows, six tanks in each row, with a clear space of 30 inches
between the tanks. The tanks or bins are 50 feet in depth, with a storage capacity of
125,000 bushels of grain each tank.”
56
The article then goes on to explain how exactly
these structures were constructed out of HCT.
The walls of the tanks are constructed with 6-inch thick semi-glazed fireproof
hollow tile, laid with the ‘hollows’ set vertical, so that the load of the contents of
the bins are brought upon the tile in the end compression. Regular courses twelve
inches in depth are continued around the tank; upon this course are laid channel or
grooved tile 4 inches in depth, ‘breaking joints’ alternate with the regular 12-inch
tile. Within the horizontal groove formed by the channel tile suitable steel bands
of the proper section area are placed and grouted into position with high-grade
Portland cement mortar, all joints being flushed full. The steel bands completely
encircle the tanks and the full tension value of the steel is maintained at

56
Ibid., 30.
35
connections by a unique lap joint, so that all points around the entire circle of the
tank the strength of the wall to resist the thrust or bursting strain is uniform
throughout.
57

The outsides of the structures are then finished with a casing tile that is both for
protection against the elements as well for architectural reasons. The HCTs create a
doublewide wall on the interior of the grain elevator and the casing tile on the outside of
the structure is hollow as well. This creates three hollow spaces separating the grain from
the outside environment, which helps control not only the temperature of the grain, but
also protects it from condensation from outside.
58
By the beginning of the 1900s, these
special grain elevator blocks were being supplied by HCT manufacturers across the
United States. The blocks were custom molded for jobs based on the diameter of the
grain elevator and included a channel at the top of each block where the reinforcing was
to be set.
59
These tiles were made with mostly fire clay, making them the most fireproof
of all HCT blocks.

Hollow Clay Tile Industry in the United States
By the 1920s, the popularity of HCT across the United States led to its standardization as
a common building material. Although, the Department of Commerce published official

57
Ibid., 30.

58
Ibid.

59
Charles E. White Jr, Hollow Tile Construction, ed. W. S. Lowndes, Ph. D. (Philadelphia: David McKay
Company, 1924), 24.
36
national standards for HCT block in 1927, standardization of size and shape was already
widespread across the industry. A distinction was clearly made between tile for
fireproofing/non load-bearing (for partition and furring) and structural tile (load-bearing).
For non load-bearing tiles: For load-bearing tiles:
Tile Size Weight Tile Size Weight
3x12x12 15 lbs 3 ¾ x12x12 20 lbs
4x12x12 16 lbs - -
6x12x12 22 lbs or 25 lbs 6x12x12 30 lbs
8x12x12 30 lbs 8x12x12 36 lbs
10x12x12 35 lbs 10x12x12 42 lbs
12x12x12 40 lbs 12x12x12 52 lbs
Furring tiles
60
3 ¾ x5x12 9 lbs
1 ½ x12x12 15 lbs 8x5x12 36 lbs
2x12x12 16 lbs 8x5x12 (L-shaped) 15 lbs
- - 8x6 ¼ x12 (T-shaped) 16 lbs
- - 8x8x8 18 lbs
- - 8x7 ¾ x12 24 lbs
- - 8x10 ¾ x12 32 lbs

Table 1: Chart showing sizes and weight of standard HCT blocks by the late 1920s. Source: Department of Commerce;
Bureau of Standards, Circular of the Bureau of Standards, U.S. Government Master Specification Tiles, Hollow, Clay,
Load-bearing Wall, No. 507, August 10, 1927; and Department of Commerce; Bureau of Standards, Circular of the
Bureau of Standards, U.S. Government Master Specification Tiles, Hollow, Clay, Fireproofing, Partition, and Furring,
No. 508, August 10, 1927.

As illustrated in Table 1, the load-bearing tiles are significantly heavier than the non
load-bearing tiles due to their higher density.

The standardization of HCT as a building material helped mainstream the material even
more and launched it to the peak of its usage by the 1930s. However, by the time HCT
had become a widespread, commonly used building material throughout the United

60
A 1 ½ x12x12 furring tile was split from a 3x12x12 tile, and a 2x12x12 furring tile was split from a
4x12x12 tile.
37
States, the building industry was growing so rapidly that other comparable building
material eventually managed to surpass HCT.

Figure 12: Advertisement for the Los Angeles Pressed Brick
Company. Source: Southwest Builder and Contractor, vol 65, no.
2 (1921), 137.
38
Timeline of Significant Events in the Development of HCT
Timeframe Event
1800’s – 1900’s Masonry load-bearing construction in combination with wood
floor joists or heavy masonry arches is one of the most
widespread systems used throughout the United States.
1813 Heavy masonry arches are used in the State House Row in
Philadelphia.
61

1854 First iron ‘I’ beam is manufactured in Trenton, New Jersey.
62

Mid-1800’s Architectural terra cotta becomes an extremely popular
building material; clay deposits in the central parts of the
United States have become fully functioning. Combination
cast iron columns and wrought iron beams are used
extensively through out construction of multi-story buildings;
heavy brick floor arches are used as fireproofing for iron.
1855 Frederick A. Peterson takes out a patent for a hollow tile floor
arch for the Cooper Institute in New York City.
1870’s The Johnson arch, a type of arch designed by George H.
Johnson, is used in the Kendall Building in Chicago.
1871 The Chicago Fire devastates the city; the annual AIA
convention is held in Chicago that year. Balthaser Kriescher
takes out a patent for a hollow tile arch.
1880 The Pioneer Fireproof Construction Company is started.
1881 The Montauk Block, in Chicago, is constructed and
fireproofed by the Wight Fireproofing Company (Peter B.
Wight).
1883 Hollow tile block is used in the Mutual Life Insurance
Company Building in New York has internal webbing in both
directions (fireproofed by the Wight Fireproofing Company).
1885 Carnegie Steel Company manufactures the first steel ‘I’
beams.
1890 Steel skeletal frame buildings are being constructed
throughout New York and Chicago.
Early 1900’s Hollow clay tile is not only being used in arches but in
partition walls by this time.
1906 The San Francisco earthquake caused major damage to
buildings throughout the city; however, no major building
codes were enacted.

61
L.R. Louis, “Hollow Tile Floor Construction – History and Present Status,” The Western Society of
Engineers 34, no. 5 (1929), 300.

62
Ibid., 299.
39
1920’s First government standards are written for the production and
use of hollow clay tile in construction.
1925 After the Santa Barbara earthquake, the city of Santa Barbara
revised a few of their building codes.
1927 First major attempt by the state of California to create unified
building codes (the Uniform Building Code).
1933 A magnitude 6.4 earthquake hit Long Beach, CA causing
severe damage to hundreds of structures. The Riley Act
finally required every city in California to have a building
department that monitors all new construction. The Field Act
is also created requiring all public schools (K-12) to abide by
building standards set by the State of California specifically
for schools.
Table 2: Timeline of significant events in the history of HCT.
40
Chapter 3: Hollow Clay Tile on the West Coast
“The enduring service of super clay products make them eminently superior for all
building construction.”
63

Hollow Clay Tile in Southern California: Clay Deposits and Tile Manufacturers
The increase in population on the west coast after the turn-of-the-century helped drive the
construction industry to great heights. As people began to move west, large cities like Los
Angeles and San Francisco became home to many new residents resulting in a huge
boom in construction. Made popular in advertising as a lightweight, fireproof building
material, HCT was produced by local brick manufacturers (see Figure 13). Brick and
HCT were the ideal building material for homes designed in the Mediterranean and
Spanish Revival styles that were growing in popularity through the Southern California
area. The large blocks could create thick walls, which is a classic characteristic of these
architectural styles. On top of this, an abundant supply of clay deposits throughout the
region made manufacturing of these materials very easy and cheap. As of 1922, a 5x8x12
size HCT block was $100/meter in Los Angeles, $117.90/meter in New York City,
$112/meter in San Francisco, and $200/meter in Albany, New York. In areas with large

63
Advertisement for Los Angeles Pressed Brick Company in Southwest Builder and Contractor, vol. 55,
no. 26, June 1920, 20.

41
clay deposits, like Ohio and Illinois, the price of a 5x8x12 size HCT block was nearly
half as much, around $50/per meter.
64

Though many of these local manufacturers were mining clay deposits in Los Angeles, the
majority of them were mining clay in the Riverside County area. Limited information is
available about the local producers of HCT between roughly 1900 and 1915, although the
California Fire-Proof Construction Company was manufacturing HCT for fireproofing
out of Riverside during this time. By 1916, the California State Mining Bureau, based out
of San Francisco, published Mines and Mineral Resources of Los Angeles County,

64
“Current Price of Common Building Brick Six Inch Drain Tile and Hollow Building Tile,” Brick and
Clay Record 60, no. 1 (1922), 44.

Figure 13: Advertisement for the Los Angeles Pressed Brick Company. Source: Southwest Builder and
Contractor, vol. 55, no. 26 (1920), 20.
42
Orange County, and Riverside County, which listed the following manufacturers as
mining clay in Los Angeles:
65

• Simons Brick Company located at 125 West Third Street, Los Angeles.
Plants included one at 1117 South Boyle Avenue in Boyle Heights, one in
Whittier, one in Santa Monica, and one in Imperial County. The Simons
Brick Company was producing HCT by 1916.
• Los Angeles Brick Company located at 503 Security Building, Los
Angeles. Plants included one located at Mission Road and Marengo Street
by the county hospital, one in Chavez Canyon, and one on Seventh Street
near Boyle Avenue.
• The Los Angeles Pressed Brick Company located at 145 South
Broadway, Los Angeles with one plant located at Alhambra Avenue and
Date Street in Los Angeles, and a second plant located in Santa Monica.
By 1916, the Los Angeles Pressed Brick Company was producing HCT
out of the Santa Monica plant.
• K & K Brick Company located at the Merchants National Bank Building,
Los Angeles with a plant on Bishop Road.
• Standard Brick Company located at 101 and 102 Stimson Building, Los
Angeles with a plant located east of the Los Angeles River.

65
California State Mining Bureau, Mines and Mineral Resources of Los Angeles County, Orange County,
and Riverside County. San Francisco, 1916, 28-38. The manufacturers listed here were not necessarily
specified as producers of HCT block in the mentioned publication. However, these manufacturers are
known to be producers of HCT as listed in Southwest Builder and Contractor from 1920 on.
43
According to the publication, the clays found in the Los Angeles area were mostly loam
clay. Loam clay is clay mixed with sand pebbles. Puente shale (a type of shale clay found
in the Puente Hills) was also found in Chavez Canyon, which was owned by the Los
Angeles Brick Company. Puente shale clay in particular makes for a highly workable
product (according to the Mines and Mineral Resources of Los Angeles County, Orange
County, and Riverside County), which is ideal for making HCT. The majority of the clay
deposits found in Los Angeles were in Boyle Heights, Inglewood, Pico Heights, Santa
Monica, Chavez Canyon, and near the Santa Fe Railroad station (abandoned by 1916).

The Los Angeles Pressed Brick Company owned a clay deposit near Temescal Valley
just south of the Santa Ana River in Orange County. This deposit was of fire clay and
considered very valuable. However, it was difficult to transport this clay across the river
to the Los Angeles plant. As of 1916, the Los Angeles Pressed Brick Company was
waiting for railroad lines to open over the river.
66
Clay deposits in Orange County and
Los Angeles were not as high quality as those in Riverside County. The clay deposits of
Riverside County were considered to be plastic clays and could be found throughout the
Temescal Valley from Elsinore to Corona.
67

The extant and thickness of these clays, together with the great plasticity of some
and the highly refractory qualities of others, give them much importance and

66
California State Mining Bureau, Resources of Los Angeles County, 59. This is a great resource for
information regarding where specific materials were mined from throughout Southern California.

67
Plastic clay refers to clay that is malleable.

44
these deposits will grow in commercial prominence as the population of southern
California increase, and transportation lines are farther developed.
68

The Alberhill Coal and Clay Company, located at 430 Union Oil Building in Los Angeles
was the largest producer of clay in the Temescal Valley. Alberhill, also located in
Riverside, supplied a large amount of clay to the Los Angeles manufacturers because of
its proximity to the terminus of the railway from Elsinore.
69

The following is list of manufacturers of masonry products located in Los Angeles that
used clay from the Riverside County area:
70

• Simons Brick Company (128 West Third Street, Los Angeles)
• Pacific Sewer Pipe Company (825 East 7
th
Street, Los Angeles)
• Los Angeles Pressed Brick Company (404 Frost Building, Los Angeles)
• Independent Sewer Pipe Company
• St. Louis Fire Brick and Clay Company (2464 East 9
th
Street, Los
Angeles)
• Ramona Tile Company (Van Nuys Building, Los Angeles)

68
California State Mining Bureau, Resources of Los Angeles County, 100.

69
Ibid., 99-144.

70
This list is provided in Mining and Mineral Resources of Los Angeles County, Orange County, and
Riverside County. Not all manufacturers listed were producing HCT specifically; however, this list is
provided to illustrate the large number of manufacturers using clay from Riverside County.
45
• Consolidated Pacific Cement and Plaster Company (San Fernando
Building, Los Angeles)
• Acme Plaster Company
• Inglewood Brick Company (Washington Building, Los Angeles)
By early 1920, manufacturers of HCT were being advertised as ‘fireproofing’
manufacturers in trade journals such as Southwest Builder and Contractor. Only two
local manufacturers were listed under this heading – the Los Angeles Pressed Brick
Company and Simons Brick Company.
71

By the end of 1920, HCT manufacturers were finally referred to as ‘hollow tile’
manufacturers. Gypsum Pro & Tile Manufacturing Company became prominent as
gypsum also grew in popularity.
72
In the 1925 volumes of Southwest Builder and
Contractor, the number of manufacturers of HCT in Los Angeles had almost doubled.
They were Los Angeles Pressed Brick Company, the Los Angeles Brick Company,
Pacific Gypsum Tile Company, Simons Brick Company, and U.S. Gypsum Company. It
is unclear whether the Gypsum Pro & Tile Manufacturing Company changed names or

71
Information on manufacturer listed in January can be found in Southwest Builder and Contractor, 55, no.
2 (1920), 26.

72
Information on manufacturer listed in June can be found in Southwest Builder and Contractor, 55, no. 26
(1920), 28.

46
possibly got bought out, but as of 1925, they were no longer listed as manufacturers of
HCT.
73

According to Southwest Builder and Contractor, by 1930, the number of manufacturers
of HCT continued to increase. Manufacturers listed at this time were Los Angeles Brick
Company, Gladding McBean & Company (Figure 14), K & K Brick Company, Simons
Brick Company, Davidson Brick Company and Higgins Brick and Hollow Building
Tile.
74
Davidson Brick Company and Higgins Brick and Hollow Tile Company were not
listed under manufacturers of HCT category however they advertised themselves as
manufacturers of HCT. By the end of the 1920s and into the 1930s, many of the brick

73
Information on manufacturer listed in January can be found in Southwest Builder and Contractor, 65, no.
2 (1925), 31.

74
Though Gladding McBean & Company was always advertised as manufacturers of terra cotta, it wasn’t
until 1930 that they began to advertise themselves as manufacturers of HCT.
Figure 14: Photo of original HCT blocks found in the United Artist Building in downtown
Los Angeles with Gladding McBean stamp. Source: photo by author.
47
manufacturers across Southern California and Los Angeles especially, were
manufacturing HCT as well.

The Fall of Hollow Clay Tile: Earthquakes, New Building Codes and Modern
Technology
A number of factors contributed to the fall of HCT nationwide – the introduction of new,
more modern building materials and the decline in the availability of raw materials for
the manufacture of the HCT due to its popularity. The west coast’s HCT industry was no
different; however, in addition to the previously mentioned factors, earthquakes played a
key role in the declining use of HCT on the west coast, but specifically in Southern
California. As a result of a number of highly destructive earthquakes, numerous new and
restrictive buildings code were put into effect that essentially outlawed the use of
construction materials such as HCT (unreinforced masonry). Cities across the state had
different versions of their own codes. After the San Francisco earthquake of 1906, city
officials did little to restrict their local building codes. In 1925, Santa Barbara revised
some of their code to require more earthquake resistant construction. This was the first
real attempt at requiring building construction standards for seismic stability. Statewide
uniform building codes for California did not exist until the first attempt was made at
creating a unified code in 1927. The Pacific Coast Building Officials (now known as the
International Conference of Building Officials) published the Uniform Building Code
(UBC) in 1927.
48
On March 10, 1933, Long Beach, CA was hit by a magnitude 6.4 earthquake. In modern
construction, an earthquake of this size would do damage, but not nearly the damage it
caused in 1933. The majority of the buildings in Los Angeles at that time were of
unreinforced masonry construction, or steel/iron skeletal frame with masonry infill (see
Figure 15). The Long Beach earthquake demonstrated the deficiencies of these structural
systems in areas with intense seismic activity. Many of the schools throughout the area
were also built of unreinforced masonry construction (especially HCT) because of its
fireproofing qualities (see Figure 16). Luckily, because the earthquake happened early in
the morning, no children were in school. More than 230 school buildings were destroyed,
damaged, or considered unfit for use.
75

75
State of California, Seismic Safety Commission, Alfred E. Alquist, The Field Act and Public School
Construction: A 2007 Perspective, (Sacramento, February 2007), 7.

Figure 15: Damage caused by unreinforced masonry buildings – note the piece of HCT in the foreground.
Source: University of Southern California Digital Library Photo Collection, “Cars covered with earthquake
debris,” Record ID: unknown, 1933.
49

As a result of the Long Beach earthquake, new building codes were enacted to increase
building safety requirements all across the United States.
76
One California law in
particular, the Field Act, was enacted to make school construction more earthquake
resistant. The Field Act requires all public schools (K-12) to abide by building standards
set by the State of California specifically for schools. The Field Act, enacted on April 10,
1933, is still in use to this day. “It has since governed the planning, design, and
construction of billions of dollars of public school (K-14) building investments.”
77

76
Along with the Long Beach earthquake of 1933, the San Francisco earthquake of 1906 and the Santa
Barbara earthquake of 1925 helped architects and engineers begin to realize traditional building methods
that moved west along with the population of the United States, were not adequate for the Western region
and needed to be altered.

77
Alfred E. Alquist. The Field Act and Public School Construction, 7. This is an important statement,
which will be addressed in the case study on the Ambassador Hotel as an example of how such changes in
building codes not only impact the use of HCT, but also the preservation of the material.
Figure 16: School in Huntington Park damaged by Long Beach earthquake. Source: University of Southern California
Digital Library Photo Collection, “High school in Huntington Park damaged by the 1933 earthquake,” Record ID: chs-
m5735, 1933.
50
Some of the requirements of the Field Act are as follows: all design standards must be
written by the Division of the State Architect (DSA) and all design plans must be
checked by DSA as well; inspectors hired directly by the school district must inspect
construction continuously throughout the building process; special tests can be ordered
by DSA if necessary; and architects/engineers must abide by the more stringent codes set
by the Field Act.
78
Also in 1933, the Riley Act was enacted that required every city in
California to have a building department that ensued that new construction of would be
able to withstand lateral thrust up to a certain point. By the 1970s, unreinforced masonry
construction was no longer allowed and all existing unreinforced masonry buildings were
required to be seismically upgraded; this is likely due in part to building codes being
strengthened again in response to the Sylmar earthquake in 1971.

Architects and engineers were beginning to understand the problems unreinforced
masonry structures presented in areas of earthquake activity, specifically on the west
coast. Unreinforced masonry (HCT falls under this category) is strong in compression
and was original designed to resist gravity loads. Lateral loads were never accounted for,
especially on the east coast where there is little seismic activity and where the
construction of masonry buildings was very successful.

Though not directly related to the fall of HCT, in 1981, the City of Los Angeles
implemented the Los Angeles Earthquake Hazard Reduction Ordinance – known as

78
Alfred E. Alquist, The Field Act and Public School Construction, 8.
51
Division 88, which required all unreinforced masonry buildings to be structurally
reinforced in the event of an earthquake.
79
This new ordinance required any existing
unreinforced masonry building to be brought up to compliance with current seismic code.
The theory behind Division 88, according to James R. McElwain in the Association for
Preservation Techology Bulletin’s article titled, “Los Angeles’s Division 88:
Consequences of Government-Mandated Rehabilitation,” is a very interesting one and
related directly to why it has become so difficult to preserve historic building materials
like HCT in the Western region:
Division 88 is explicitly intended to preserve life rather than preserve buildings…
Wood frame, steel, and reinforced concrete structures, even those with non-
bearing masonry walls or infill, are not covered by Division 88 because they are
not believed to be in the same danger of catastrophic collapse as unreinforced
masonry building. Thus, under the Los Angeles code, building may be allowed to
suffer unrepairable structural and architectural damage so long as they do not
actually fail during an earthquake. This damage may include masonry cracking,
wall dislocation and destruction of non-bearing plaster partitions.
80

When the code was enforced, owners of unreinforced masonry buildings had three
options: to strengthen their buildings, evacuate tenants from them, or demolish them.
Because structural strengthening of an existing building can be very costly, especially for

79
James R. McElwain, “Los Angeles’s Division 88: Consequences of Government-Mandated
Rehabilitation,” APT Bulletin 24, no 1/2 (1992), 22. The mention of Division 88 here is to show how
changes in building codes not only made it difficult for architect and engineers to construct buildings with
HCT, but also such changes in building codes have made it difficult to preserve such materials as well.

80
Ibid., 22-23.
52
a small apartment building, many people demolished historic and older unreinforced
masonry buildings resulting in a loss of historic building stock in Los Angeles, along
with a great deal of historic building components.

In California, western framing (wood construction) was the most popular form of
construction for new low-scale buildings as it is far more ductile in earthquakes and was
less expensive due to the abundance of trees throughout the west coast. Along with the
changes in building codes and the acknowledgment that masonry construction did not
perform well in areas of high seismic activity, a number of new, modern building
materials were also making their way into the mainstream and would eventually replace
HCT as a building material. As Western wood frame construction again became the most
widespread construction method after the 1933 earthquake, manufacturers needed to
develop building materials that would replace the fireproof qualities of HCT and other
masonry materials. Besides wood frame construction, steel skeletal and reinforced
concrete frame buildings were generally the choice of construction method for multi-
story buildings.
81
Concrete block and gypsum block were two building materials that
developed around the time HCT peaked in popularity. Concrete block and gypsum block
could replace HCT in situations where a fireproof infill material was needed (gypsum
block), or on its own as a structural load-bearing unit (concrete block).

81
The use of HCT for partition walls for these types of buildings was still somewhat common into the
1940s; however, with the decline of buildings constructed completely out of structural HCT, the production
of HCT slowed dramatically.
53
Gypsum block had good fireproof qualities but no structural capability. Gypsum block is
made of plaster of Paris (calcined gypsum) with the addition of a small percentage of a
fibrous material like wood. “In 1903 the United States Gypsum Company’s Genesee,
New York, plant began production of gypsum tiles, which it marketed as a fireproof
replacement for clay tile in non-load-bearing situations.”
82
Gypsum block had a number
of beneficial qualities that outweighed the use of HCT. Gypsum block was fireproof so it
could be used around structural steel and in partition walls, it also had soundproofing and
insulation qualities, was very workable and could be cut down easily, and was low in cost
to manufacture and transport because the blocks were not very fragile. Another quality
was that they were large and lightweight, which meant fewer blocks needed to be used to
fill a designated area.
83

82
Susan M. Escherich. “Gypsum Block and Tile,” in Twentieth Century Building Materials; History and
Conservation, ed. Thomas C. Jester, (McGraw-Hill Companies, 1995), 163.

83
Ibid., 162-167.
54
CMU (concrete masonry units) or just ‘concrete block’ is still used throughout modern
construction. The birth of the CMU is attributed to the invention of a machine, patented
in 1900 by Harmon S. Palmer that could quickly and easily manufacture the blocks.
84

Part of the reason why the use of concrete block grew so quickly in the beginning of the
twentieth century was because of the improvements in concrete mix due to the
availability of Portland cement. “In 1919, 50 million concrete blocks were produced in
the United States; in 1928 that number had increased to 387 million.”
85
The material
composition of concrete blocks made them very strong, especially in earthquake zones. A
number of industry associations formed in the 1920s, including the Concrete Block
Machine Manufacturers Association and the Concrete Block Manufacturers Association.
A structure built out of concrete block also has the benefit of being fireproof, soundproof,
and well insulated. With the availability of different options in building materials, HCT

84
Pamela H. Simpson. “Concrete Block,” in Twentieth Century Building Materials; History and
Conservation, ed. Thomas C. Jester, (McGraw-Hill Companies, 1995), 80.

85
Ibid., 82.
Figure 17: Advertisement for Gypsum Hollow Building and Partition Tile. Source: Southwest Builder and Contractor,
vol. 55, no. 26, (1920), 31.
55
was slowly losing its popularity, especially on the west coast. As mentioned previously,
along with the of new block products, materials were invented to replace lath and plaster,
but which also provided additional qualities such as fireproofing.

Along with the discovery of gypsum for blocks, manufacturers began making gypsum
board as well. Gypsum board was first patented in the end of the 19
th
century. It was
originally 32 x 36 inches and was composed of six layers of felt paper. Sandwiched
between each layer of felt paper was a layer of gypsum; however, each board varied in
thickness.
86
Gypsum board became increasingly popular shortly before WWI when
standardization of the board helped streamline the manufacturing process. Also, gypsum
board provided a number of qualities found in other building materials at a much lower
cost. “Because of its cost advantage over wood and particularly its fire resistance,
gypsum board began to displace wood and metal lath for plaster backing by World War
I.”
87
Sheetrock wallboard and tile board were offshoots from the gypsum board
manufacturers. By the time WWII rolled around, materials that could be easily
manufactured, and could replace wood and metal, were used extensively throughout the
United States.
88

86
Kimberly A. Konrad and Michael A. Tomlan, “Gypsum Board,” in Twentieth Century Building
Materials; History and Conservation, ed. Thomas C. Jester, (McGraw-Hill Companies, 1995), 269.

87
Ibid., 270.

88
Materials such as lumber and metal were needed for the war and were considered off limits for non war
related construction in the United States.

56

Another material, similar to gypsum board, was fiberboard (Beaver Board, Masonite,
Upson Board). Fiberboard could be used to replace HCT in wood frame construction. It
had fireproofing qualities and could be used as structural sheathing. Fiberboard is made
of wood fiber (or another vegetable fiber). The Beaver Board Company, based out of
Beaver Falls, NY, was considered to be the most prolific manufacturers of fiberboard
because nearly six patents were awarded to employees of the company for fiberboard
products.
89
Masonite, a hardboard manufactured by the Mason Fiber Company, had made
its way into the industry by the late 1920s. Masonite was much stronger then average
fiberboard because it was pressed at higher temperatures for longer periods of time and
was much stronger.
90
Fiberboard products revolutionized the building industry around the
time of WWII.

Housing shortages in the 1930s drove the development of numerous insulation and
wallboard products. Just before World War II, manufacturers such as Homasote
developed specialized products for prefabricated housing, such as the Precision Built
Home system, that allowed for the construction of 977 Vallejo, California, houses in 73

89
Carol S. Gould, Kimberly A. Konrad, Kathleen Catalano Milley, and Rebecca Gallagher, “Fiberboard,”
in Twentieth Century Building Materials; History and Conservation, ed. Thomas C. Jester, (McGraw-Hill
Companies, 1995), 122.

90
Carol Gould. “Masonite: Versatile Modern Material for Baths, Basements, Bus Stations, and Beyond,”
APT Bulletin 28, no 2/3 (1997), 65.

57
days.
91
By the 1940s, when veterans returned home from war, the shortage of housing
called for an increase in materials production and labor for the construction of new
housing. Materials that were easy to manufacture, transport, and construct began to edge
out number the more archaic construction materials that had been used for years.

91
Gould, Konrad, Milley, and Gallagher, “Fiberboard,” 122.
58
Chapter 4: The Preservation of Hollow Clay Tile
Historic significance can never be permanently canonized because concepts of
historical significance are always subjective and must be periodically,
thoughtfully revisited and redefined… so that [our resources] are preserved from
all unnecessary manipulation so that they may retain the wholeness of their truth
for generations to come.
92

Building a Case for Maintaining Integrity
Preserving HCT is both important and possible. In order to fully demonstrate why this
statement is true, it is important to understand the evolution of the field of historic
preservation and where the preservation of building materials, such as HCT, fall within
this evolution. The Secretary of the Interior allows for different treatments of historic
buildings and depending on the treatment approach, the preservation method is slightly
different. The most common treatment approach is Rehabilitation - this approach allows
for a new use of an historic structure and typically is the least strict approach.
Preservation allows for historic structures to be preserved in their current condition and
maintained. Restoration is more strict because historic structures are brought back to a
period of time considered historic to that specific structure. The most strict approach is

92
W. Brown Morton quoted in David G. Woodcock’s article titled “Encouraging Excellence While
Maintaining Standards: An Ongoing Discussion,” APT Bulletin, Vol. 37, No. 4 (2006), 47.

59
Reconstruction which allows a no longer extant historic structure to be reconstructed.
93
In
general, the guidelines encourage preservationists to identify all historic, character
defining features of a resource, preserve and maintain such features, and if that is not
possible, then repair them. If repair is not an option, replacement in-kind is the preferred
solution. This applies to architectural features, historic spaces, and original materials.

Building materials have historically been valued as secondary to architectural aesthetics
in the preservation movement.
94
A building’s integrity is defined by a number of different
elements including its materials, workmanship and association, among others.
95

Materials include those both visible/aesthetic and those not visible/structural.
Historically, the preservation movement has been known to place historic value on those
structures of high artistic merit or that have played a role in shaping our history. Before
the National Historic Preservation Act of 1966, preserving historic structures generally
meant preserving an aesthetically beautiful building and turning it into a house museum

93
The Secretary of the Interior Treatment Approach, published by the National Park Service, is mentioned
here for a number of reasons. One, because it is important to understand that depending on what approach
is selected, the treatment of the historic fabric will be different, and this applies to originally building
materials like HCT. Second, the case studies, which will be address in the second part of this chapter, will
illustrate how the treatment of the HCT differed depending on the approach that was chosen.

94
That is unless a building material is part of the aesthetics of the architecture such as the iron frame of the
Eiffel Tower.

95
Integrity, as defined by the Secretary of the Interior, is comprised of seven different elements: location -
this original place the resource was constructed or where the significant event occurred; design - the layout,
style, form, etc that creates the overall design of the resource; setting - the environment the resource was
originally set in; materials - the original physical elements that made up the resource; workmanship - the
physical record of the craftsman that built the resource; feeling - the aesthetic expression of the resource as
it gives in its setting; and finally association - the link between an event in the history of the culture and the
resource.
60
to be viewed by visitors. As preservation evolved, the focus shifted from that of
structures of high artistic merit to those of cultural significance – ‘worth’ has become a
more broad term. The role the resource has played in the overall development of our
culture and those things that we consider historically significant now define value. This
has in turn placed a higher value on the different components that make a building
historic – including its materials, both visible and invisible. This idea is summed up well
by Sharon C. Parks when describing the basis of the Secretary of the Interior’s Standards.
The standards were based on the premise that the tangible aspect of a resource
was its link to history and the basis of its significance. The value that has been put
on preservation is that the design intention and achievement as evidenced in the
quality of construction, craftsmanship, details, finishes, and the resultant spaces
are all part of the resource and must be evaluated and protected.
96

The materials that make up a structure are referred to as a structure’s historic fabric. Over
time, interest in materials and the preservation of such materials has grown and become
just as significant as a resource’s design. As a result, those interested in preservation have
expanded from historians and architects to engineers, materials conservators, and private
homeowners who want to maintain their own historic home – leading to an expansion in
the types of buildings that are now preserved.

96
Sharon C. Parks. “Respecting Significance and Keeping Integrity: Approaches to Rehabilitation,” APT
Bulletin 37, no. 4 (2006), 20. In 2006 when the article cited was written, Sharon C. Parks was the Chief of
Technical Preservation Service’s Heritage Preservation Assistance Programs for the National Park Service.
61
Other changes in the preservation movement have drawn the attention of people
traditionally less interested in preserving historic structures. In the 1980s, modifications
to the national tax code allowed for tax incentives to preserve historic buildings.
97
These
changes helped spur interest from the private sector to preserve historic buildings. Private
sector interest eventually led to an increase in development and the adaptive reuse of
historic buildings, especially in dense downtown urban areas. Compliance with the
Secretary of the Interior’s Standards for Rehabilitation is required in order for the project
to receive these tax credits. As a result of this, many developers became involved in the
preservation movement as a means of creating income. This proved to have both positive
and negative effects on the preservation of historic buildings. The incentives have shed
light on yet another effective way historic buildings can be preserved and reused, and
helped revive many urban areas that were previously abandoned and not popular places
to live. However, this increased interest in the reuse of historic structures – if in the
wrong hands – can lead to a loss of much of the valuable historic fabric of these buildings
as a means of cutting costs. When little monetary value is placed on original materials of
a structure (ie: original HCT walls), developers find no reason to preserve them and they
are often times removed. This is where preservationists come in - preservationists,
including architects, engineers, conservators, non-profits, and city employees, can all
advocate for the preservation of historic fabric if they understand the importance these
materials have played in shaping our culture and especially our built environment.

97
The 20% Rehabilitation Tax Credit and the 10% Rehabilitation Tax Credit were both issued into the tax
code by the Tax Reform Act of 1986. Both credits allow for a tax credit for rehabilitated historic structures.
62
Referring back to the three elements of integrity listed previously (material,
workmanship, and association), the most obvious value of HCT in a historic building is
as an original building material. Secondarily, HCT is often times constructed adjacent to,
or as part of, character-defining features – it is an integral part of a resource’s significant
spaces. In downtown Los Angeles alone, any multi-story building built between 1910 and
1940 of steel skeletal frame or reinforced concrete frame construction most likely has
HCT. The association HCT has in such buildings is valuable based on the history and the
role the material played in the evolution of building practices in the United States.

Though not necessarily considered historic in its own right (as defined by the National
Register’s criteria for evaluating historic resources), HCT is almost always an integral
part of significant spaces throughout a historic building and plays a role in telling the
story of that structure.
98
Because this is often the case, preservationist must make
decisions about how to preserve an archaic material like HCT and do so in a way that
does not jeopardize any additional historic fabric. The role HCT now plays in
preservation is an interesting one. Although it has proven itself as an important building
material, the nature of the material has made it a difficult one to preserve. As has been

98
As published by the National Park Service, the National Register criteria for the evaluation of historic
resources is as follows: A) That are associated with events that have made a significant contribution to the
broad patterns of our history; or B) That are associated with the lives of significant persons in or past; or C)
That embody the distinctive characteristics of a type, period, or method of construction, or that represent
the work of a master, or that possess high artistic values, or that represent a significant and distinguishable
entity whose components may lack individual distinction; or D) That have yielded or may be likely to
yield, information important in history or prehistory. This information can be found at the following
website: http://www.nps.gov/nr/publications/bulletins/nrb15/nrb15_2.htm.

63
mentioned throughout this thesis, HCT can be fragile due to its material composition and
its structure, causing it to be even more vulnerable to seismic activity. Many people
believe that because of the fragility of this material, in any circumstance, it cannot be
saved, nor should it be saved. Often times, excuses are used to justify why preserving it is
not possible, such as costs to retrofit/reinforce the material and life-safety issues. In the
next section of this thesis, five case studies will illustrate how HCT was preserved,
proving that it can be done.

Nearly all the case studies in this next section have happened in the last five years. The
purpose of these case studies is to provide preservationists with a tool to begin the
conversation of why preserving HCT is important and how it can be done. Information
for each project will include the architect, historic architect and engineer, as well as a
quick synopsis of the history of each case study and the solution for saving the HCT. All
involved in the restoration of these buildings were advocates for preserving as much
historic material as possible.

64
Case Study No. 1: Swan Hall at Occidental College
Los Angeles, CA

Restoration Project Team:
Owner: Occidental College
Architect: Brian Bowen
Historic Architect: Unknown
Engineer: John A. Martin and Associates

BRIEF HISTORY: James Swan Hall, originally constructed as an all male dormitory, is
located on the campus of Occidental College in Eagle Rock, California. Myron Hunt, a
prolific Southern California architect who designed a number of notable buildings
through Los Angeles, designed Swan Hall. Other notable buildings by Myron Hunt
Figure 18: Historic photo of Swan Hall. Source: Photo by unknown, “Swan Hall at Occidental College,” Los
Angeles Public Library.
65
include the Pasadena Public Library, The Huntington Hotel, and the Ambassador Hotel.
99

The layout of Swan Hall posed a number of problems for engineers when it came time to
seismically retrofit the building. The building is constructed on a sloping site (from east
to west). To accommodate this, the architect designed it so that there is an internal step
down from the front of the building, to the back (east to west). To further confuse things,
the central section of the structure is stepped up, internally, between the north and south
sides (see Figure 19).
100
The architectural style of Swan Hall is Spanish Revival, with
Italian influences.
In a 1914 Los Angeles Times article, the author describes the building as “of the most
permanent construction of steel and concrete, with terra cotta tile and are absolutely
fireproof and indestructible as it is possible for buildings to be. They are rather severe in

99
David Kaplan and Pam O’Connor, Kaplan Chen Kaplan Architects. “Occidental College, Swan Hall
Rehabilitation and Addition: Historic Resource Impact Report,” dated September 20, 2010, 2.

100
Ibid., 6.
Figure 19: Original construction drawing by Myron Hunt of Swan Hall, sections looking North and South. Source:
courtesy of John A. Martin and Associates.
66
their plainness, but admirable for the purposes of education.”
101
Research has shown that
Myron Hunt constructed a number of his buildings out of HCT, most likely due to its
popularity as a fireproof material. In the case of Swan Hall, the HCT is used as infill
between the concrete structural systems. The interior partition walls of HCT were
removed in the 60s when the dormitory was made into office. The majority of the historic
building’s exterior is original, except for a few repairs due to earthquake damage.

WHY CASE STUDY WAS CHOSEN: Swan Hall is a prime example of the preservation
of HCT infill walls. Swan Hall is not currently landmarked; both the college and the
community acknowledge that it is as historic resource. For the rehabilitation of this
historic building, the structure needed to undergo a large seismic retrofit. It was also
given a new use, as it was originally built as dorms and was transformed into offices.
Kaplan Chen Kaplan’s 2010 report, titled “Swan Hall Rehabilitation and Addition
Historic Resource Impacts Evaluation,” characterizes the HCT as a character-defining
feature and a historic material original to the construction of Swan Hall.
102
The first
paragraph of the section titled Swan Hall Existing Materials and Character-Defining
Features creates a strong foundation for why the HCT at Swan Hall is an important
feature of the building.

101
“Glad Day Now For Occidental: Buildings on New Campus to be Dedicated,” Los Angeles Times,
March 26, 1914, II2.

102
Kaplan and O’Connor, “Occidental College,” 7-8.
67
Historic character, while generally focused on visible and visual aspects of the
building, also relates to the retention of original materials. The Secretary of the
Interior’s Standards for Rehabilitation refers to both the removal of historic
materials as well as the alteration of features and spaces that characterize a
property. The original materials as well as the construction technology and
methodology are contained within the existing building and are fundamentally
part of the historic character.
103

The report goes on to say,
The hollow clay tile was an important advance in the fireproofing of buildings
and was used extensively at the time… Construction with hollow clay tile finished
with plaster was common for Myron Hunt’s buildings and similar to the
Ambassador Hotel except for the use of the double wall in Swan Hall where the
returns for the windows may provide added strength to the assembly.
104

The importance of preserving the exterior façade of Swan Hall (which is a character-
defining feature of the structure) made it crucial to preserve the HCT walls. In this
building, the historic exterior stucco finish was laid on a doublewide HCT wall, meaning
the HCTs were laid with both an exterior wall and an interior leaving an airspace in
between the two walls. This allowed engineers to remove the interior HCT wall and
reinforce the exterior wall from the inside.

103
Ibid., 7.

104
Ibid., 8.
68
PRESERVING THE HCT: The structural engineer that worked on this project was John
A. Martin and Associates based out of Los Angeles. John A. Martin and Associates has
experience with historic buildings, including a number of Myron Hunt buildings, like the
Huntington Library. To structurally strengthen the exterior HCT walls, “L” shaped
anchors were drilled into the HCT and epoxied into place (see Figures 20 & 21). The
location of anchors was determined by the coverage area of the epoxy for each anchor
inside the tile where the anchor was inserted. Once the anchors were secured into place,
the walls were shotcreted from the inside so that the anchors would hold the HCT to the
shotcrete. This system allowed for the shotcrete to replace the interior HCT wall and still
maintain original wall thickness around windows and doors – the shotcrete was made the
same width as the original walls.
Figure 20: Photo of new 'L' bracket epoxied anchors inserted into original HCT wall, ready to receive new
shotcrete. Source: courtesy of John A. Martin and Associates.
69

Additional structural upgrades to the building included the construction of periodic
concrete shear walls in the interior of the building (see Figure 22). These shear walls
serve to seismically stabilize the building in an earthquake. Because the two short ends of
the building were badly damaged in a previous earthquake, and the exterior stucco in
these two locations was not original, engineers used these two locations for additional
concrete shear walls.

WHAT WAS LEARNED: This case study clearly illustrates a straightforward seismic
strengthening of the HCT at Swan Hall. In this case, the engineers were fortunate the
HCT walls were double width and the interior wall could be sacrificed in order to
OCCIDENTAL COLLEGE
JAMES SWAN HALL
1600 CAMPUS RD.
Architect
(909) 390-7209
ARCHITECTURE AND PLANNING
350 S. Milliken Ave., Ste. G, Ontario, CA 91761-7850
FAX: (909) 390-7509
Brian R. Bloom
SECTIONS
AND DETAILS
S4.8
Figure 21: Detail 5 illustrates where and how the new epoxy anchors will be
attached to the existing HCT wall. Source: courtesy of John A. Martin and
Associates.
70
preserve the exterior wall. The original, historic finish was preserved, along with one of
the original building materials – the HCT. Significantly, HCT was identified as an
historically significant material. It was possible to save the HCT infill in the structural
framing using modern building technology. The HCT infill walls were backed with
shotcrete walls, but in an effort to further strengthen the building, the engineers also took
advantage of areas that were not considered historically significant to add additional
shear walls. This same system can easily be replicated in other projects.

SECOND FLOOR FRAMING PLAN
N
OCCIDENTAL COLLEGE
JAMES SWAN HALL
1600 CAMPUS RD.
Architect
(909) 390-7209
ARCHITECTURE AND PLANNING
350 S. Milliken Ave., Ste. G, Ontario, CA 91761-7850
FAX: (909) 390-7509
Brian R. Bloom
SECOND FLOOR
FRAMING PLAN
S2.2
Figure 22: Floor plan of Swan Hall, red arrows indicate locations of new concrete shear walls. Source: courtesy of
John A. Martin and Associates.
71
Case Study No. 2: The Riverside Metropolitan Museum
Riverside, CA

Restoration Project Team:
Owner: City of Riverside
Architect: Drisko Architecture
Historic Architect: Drisko Architecture
Engineer: Structural Focus
BRIEF HISTORY: The Riverside Metropolitan Museum is located in Riverside,
California. Originally built as the Riverside Post Office in 1912 by James K. Taylor
(constructed by the Southwestern Construction Company), it is now home to the
Riverside Metropolitan Museum. The two-story structure (with attic) was designed in the
Mission Revival style with classical elements.
105
The property was designated a local
landmark in 1969, is a local district contributor, and is listed on the National Register of
Historic Places.

105
City of Riverside online historic property database can be found at:
http://olmsted.riversideca.gov/historic/.
Figure 23: Current photo of Riverside Metropolitan Museum taken February 11, 2012. Source: photo by author.

72

WHY CASE STUDY WAS CHOSEN: The seismic stabilization of the Riverside
Metropolitan Museum illustrates how HCT is preserved in a situation where the material
poses a safety hazard if it fails in an earthquake (life/safety issue). In this case study, the
HCT is found in the wall of the interior light court in the attic of the building (see Figures
24 & 25). Often, HCT can be used in corridors, elevator lobbies and light wells. In an
earthquake, the HCT can become hazard if it crumbles and block the means of egress.
Figure 24: Building section indicates location of HCT light well within the attic space (yellow area). Source:
courtesy of Structural Focus.
73
In this case, because the HCT could fall into the light court during an earthquake, it
needed to be mitigated. Even though the HCT walls in this case study are not necessarily
an integral part of any character-defining features, saving the HCT was more practical
than removing it mainly for cost reasons. To remove the HCT and replace the wall with
new materials would have been more costly then simply reinforcing the existing HCT
wall. This is a good example of a situation where saving the HCT was actually a less
expensive solution.

PRESERVING THE HCT: Engineer David Cocke of Structural Focus was hired to
provide a limited seismic retrofit of the historic structure. One aspect of the seismic
retrofit was to stabilize the HCT walls of the central skylight located in the attic. In the
event of an earthquake, the walls could potentially fall out of plane, due to their lack of
reinforcement, and cause serious damage to the building and those in or around it.
Bracing needed to be added to reinforce the walls. To do so, Structural Focus’ design was
Figure 25: Partial attic plan view showing location of HCT walls in the light well. Source: courtesy of Structural
Focus.
74
to create an exterior brace for the HCT for all four walls of the skylight structure. Bracing
consisted of light gauge metal studs, which act as strongbacks for the HCT, and span
from the floor to the roof (see Figure 26). Each stud, spaced 16” on center, is anchored to
the HCT wall with 3/8” bolts. The bolts are threaded through the HCT wall and attached
to a ¼” x 4” continuous bearing plate that runs horizontally along the entire interior of the
skylight (see Figures 27 & 28). This bearing plate creates a steel band that holds the
entire structure together.
106
This structural design is a good alternative for a smaller scale
seismic reinforcing of HCT.

106
David Cocke, e-mail message to author dated January 26, 2012.
Figure 26: Photograph showing the light gauge metal framing used to reinforce the HCT walls in the light
well. Source: courtesy of Structural Focus.
75

Figure 27: Detail 11 illustrates bracing of HCT to new light gauge metal
frame. Source: courtesy of Structural Focus.
Figure 28: Photo showing interior bearing plate for reinforcing of the HCT from inside of light
well (indicated by red arrows). Source: courtesy of Structural Focus.
76
The Riverside Metropolitan Museum design does double duty as it not only reinforced
the HCT, but the light gauge studs can also be used for interior furred out wall. Because
the reinforcing for this project was for the HCT wall of the skylight, there was no historic
interior finish that needed to be preserved. In the case of a furred out wall, the steel studs
can be used to attach the interior finish in cases where the original interior either has been
lost or is not considered historic.

WHAT WAS LEARNED: HCT can be saved in situations where it is a potential safety
hazard. HCT was often used in hallways, stairwells and light wells and is a risk of failing
and falling into exit corridors in earthquakes. The system used for the retrofit of the
Riverside Metropolitan Museum proves that even in situations where HCT is a potential
safety hazard, it can be mitigated and preserved, and is sometimes even the most cost
effective option.

77
Case Study No. 3: The Mission Inn
Riverside, CA

Restoration Project Team:
Owner: Historic Mission Inn Corporation
Architect: Unknown
Historic Architect: Architectural Resources Group
Engineer: Unknown

BRIEF HISTORY: The Mission Inn, probably considered Riverside’s most valuable
resource (City Landmark #1), was designed by Frank Miller and constructed by Boggs,
Wilcox and Rose. The Mission Inn is considered California’s largest Mission Revival
building. Originally called the Glenwood Cottage, the structure began as a modest hotel
constructed of adobe bricks. The original Glenwood Cottage (built in 1876) was
Figure 29: Exterior shot of Mission Inn, looking towards the Rotunda Wing.
Source: courtesy of the Mission Inn website: www.missioninn.com
78
demolished in 1948 to make room for a swimming pool, which still exists today.
107

However, the many additions to the Mission Inn still stand and each wing is slightly
different in design and construction.

The Mission Wing (see Figure 30) is constructed out of unreinforced brick exterior with
heavy timber framing. This wing is designed in a U-shape with a central corridor, which
also acts as the main support wall. The Cloister Wing (dark yellow area in Figure 30) was
constructed between 1909 and 1911 and was designed by Arthur Benton. The basement
and first floor are constructed of concrete and brick with concrete and brick walls, and
concrete beams and floor slabs. The upper floor exterior walls are of brick and the

107
All property information regarding the Mission Inn is from the City of Riverside online historic property
database can be found at: http://olmsted.riversideca.gov/historic/, unless otherwise noted.
Figure 30: Axonometric view of the Mission Inn illustrates the many wings of the hotel and their dates of
construction. Source: “The Historic Mission Inn,” ed. Barbara Moore. Friends of the Mission Inn: 2007, 18-
19.
79
interior walls are of HCT covered with plaster. In 1924, a fourth floor of rooms was
added to this wing and is constructed of HCT.

Architect Myron Hunt designed the Spanish Wing (circled area in Figure 30) in 1914.
Frank Miller traveled across much of Europe, often times to Spain and Italy collecting
items that are incorporated throughout the hotel, such as fountains, fireplaces, grilles,
tiles, and bells, both as decoration and as furniture. The original construction of this wing
is of reinforced concrete, but in the 1920s, a third and fourth floor was added. Arthur
Benton and G. Stanley Wilson designed this addition. The majority of the addition is also
constructed out of reinforced concrete, except for the fourth floor, which is constructed
Figure 31: Mission Inn Spanish Wing, fourth floor taken on February 11, 2012. Source: photo by author.
80
out of HCT (see Figure 31). The International Wing (or Rotunda Wing) built from 1929 –
1931, takes up the entire northwest corner of the Inn. This addition is constructed out of
reinforced concrete, except for the fourth floor rooms, which was also constructed out of
HCT.

WHY CASE STUDY WAS CHOSEN: The Mission Inn is a good example of preserving
HCT in a situation where it is not only original historic fabric but it also serves as the
finish material for some interior and exterior walls. The exposed HCT is a distinctive
character-defining feature of the Mission Inn (see Figures 31 & 32). The Mission Inn
project was a rehabilitation project because not only did the structure need major
retrofitting, but also a lot of the old hotel was modernized to meet the current needs of
their guests. In the 1980s the building went through a major rehabilitation and seismic
retrofit.
108
Because the HCT was visible and a character-defining feature, the Mission Inn
challenged the engineers to design a seismic retrofit that preserved the HCT. Preservation
of the HCT at the Mission Inn was crucial because it is an integral part of the historic
façade.

108
Bruce Judd, now an independent consultant, but at the time a principal with Architectural Resources
Group, was on the team of architects and engineers who worked on the Mission Inn project.
81
PRESERVING THE HCT: A number of designs were implemented throughout the hotel
Figure 32: Photo of original ruffled exterior HCT at
the Mission Inn on February 11, 2012. Source: photo
by author.
Figure 33: Original floor plan of the Mission Inn Rotunda Wing. Note callout for '8" HT', original 8" HCT walls which
were retrofitted with new shotcrete walls. Source: courtesy of the Mission Inn Foundation and Museum Archives.
82
PRESERVING THE HCT: A number of designs were implemented throughout the hotel
for structural stabilization. For purposes of this thesis, only the structural stabilization of
the HCT will be addressed. One challenge of preserving the historic finish of the glazed,
ruffled HCT on both the interior and exterior was to leave the exposed HCT in place. The
majority of the hotel rooms constructed out of HCT are on the upper floors of the
Rotunda Wing and the Spanish Wing. In these locations, structural reinforcing was
executed by removing one side of the HCT walls and adding a layer of shotcrete the same
thickness as the original thickness of HCT (see Figure 33.) This allowed the engineers to
maintain a portion of the original HCT, while strengthening the wall at the same time.
Gladding McBean, the original manufacturers of the HCT, made custom thin “façade”
tiles that were then used as veneer over the shotcrete in order to create the same
appearance and thickness of the original ruffled HCT.

Another structural reinforcing technique used for the retrofit was to strengthen the HCT
buttresses on the fourth floor of the Spanish Wing. The interior of the buttress was
hollowed out, and reinforced with a new steel column. This technique tied the buttress to
the concrete floor slab (see Figure 34). Once the reinforcing was complete, the openings
were finished with a veneer brick made to match the adjacent HCT.
83

WHAT WAS LEARNED: The Mission Inn case study illustrates a solution for
preserving the look and aesthetics of HCT used as a finish material. Not only is the HCT
at the Mission Inn an integral part of the historic finish, but it is also a part of the
structure of the building. The technique used to reinforce the interior walls, which are
finished on both sides with exposed HCT, was very creative and effective.

Figure 34: Photo showing the structural strengthening of
the HCT buttress at the Mission Inn. Source: courtesy of
Bruce Judd.
84
Case Study No. 4: The Hollyhock House
Los Angeles, CA

Restoration Project Team:
Owner: City of Los Angeles
Architect: Bureau of Engineering
Historic Architect: Many
Engineer: Melvyn Green & Associates, among others

BRIEF HISTORY: The Hollyhock House, located in Hollywood, California was
originally designed by architect Frank Lloyd Wright for Aline Barnsdall. The house is
Figure 35: Main entrance to the Hollyhock house, looking towards the living room, pool in foreground.
Source: University of Southern California Digital Library Photo Collection, Record ID: chs-m30286, 1932.
85
located on Olive Hill, which was purchased by Barnsdall in 1919.
109
Wright, designed
Hollyhock House based on the natural topography of the site.
The plan included a theater along the eastern slope, a large residential building set
prominently at the crest of the hill, a director’s residence, and an apartment
building, called the ‘Actor’s Abode.’ Wright drew the first general plan for Olive
Hill in 1919, which included Barnsdall’s residence, a director’s residence, guest
house, theater, and apartment building. On Barnsdall’s direction, Wright revised
the plans in 1920, making the residences the first part of a phased approach, with
the theater and apartments part of a Phase II plan that was also to include a
commercial component.
110

Wright left architect Rudolph Schindler in charge of completing the project when he left
for Japan to complete the construction of the Imperial Hotel. Originally designed to look
as if it was built entirely of concrete, Hollyhock House is actually a wood stud frame with
HCT infill and finished with stucco to mimic concrete (see Figure 35.) Decorative
symbolic Hollyhock cast stone pieces line the perimeter of the house and are used as
accents throughout, such as the planter boxes located by the terrace, which was designed
and built by Schindler. The Hollyhock House is a National Historic Landmark.

109
LSA Associates, Inc and Chattel Architecture, Planning and Preservation with contributions by CK Arts,
Melvyn Green and Associates, Smith-Emery Laboratories, Independent Waterproofing, Addison Pools and
Cumming Corporation. Supplemental Historic Structure Report; Hollyhock House, City of Los Angeles.
October 2009, 5.

110
Kathryn Smith, Frank Lloyd Wright, Hollyhock House and Olive Hill, Rizzoli International
Publications, New York, NY, 1992, 53 as quoted in the LSA Associates, Inc and Chattel Architecture,
Supplemental Historic Structure Report.
86
WHY CASE STUDY WAS CHOSEN: This case study demonstrates a situation in which
an original building material (HCT) is treated as part of the historic fabric and any repairs
to the structure cannot jeopardize the HCT. The interior walls constructed of HCT define
the spaces of the house, which is one if its character-defining features. This is an example
using the preservation treatment approach, which values the original historic fabric very
highly. The Hollyhock House has gone through a number of different owners, has been
remodeled a number of different times, and has had to go through several restorations to
repair damage, mainly due to water infiltration and structural instability. A structural
retrofit of the Hollyhock House and Residence A was done in May 2001. The 2001
seismic retrofit included “inserting structural steel and anchoring systems to improve the
Figure 36: Original plan of the Hollyhock House, red arrow indicates location of
HCT retaining wall. Source: Hawthorne, Christopher. “Frank Lloyd Wright
Auction Has LA Connection,” Los Angeles Times, February 6, 2012.
87
bracing and stability of the cement block and hollow clay tile (HCT) wall to the wood
framed and stucco roof. The steel beams were installed in the living area, on the loggia
columns, and roof support systems near the main entrance.”
111
Currently, the Hollyhock
House is implementing a phased restoration plan, including both preservation and
retrofitting of the HCT walls on both the exterior and interior.

PRESERVING THE HCT: Although there has been some structural strengthening of the
HCT in areas throughout the house, there continues to be the question of how to reinforce
the HCT without sacrificing historic finishes that exist on both sides of the same wall.
The garage, originally constructed with load-bearing HCT but without the same level of
historic interior finishes, has been brought up to full compliance with the Los Angeles
Earthquake Hazard Reduction Ordinance, Division 88. The structure has a steel

111
LSA Associates, Inc and Chattel Architecture, Supplemental Historic Structure Report, 9.
Figure 37: Photo of historic interior HCT walls at the Hollyhock House near the library, taken February 2, 2012. Source:
courtesy of Preservation Arts.
88
diaphragm system running horizontally across the top of the walls to brace them
together.
112

The Hollyhock House is a perfect example of preservation because every aspect of its
construction and all remaining original materials are treated like relics of its history. As
such, repair of the exterior terrace wall is to be done in such a way that it will not

112
This information was provided by Melvyn Green, of Melvyn Green and Associates in an e-mail to the
author dated February 4, 2012.
Figure 38: Photo showing the exterior HCT terrace wall at the
Hollyhock House, taken February 2, 2012. Source: courtesy of
Preservation Art.
89
sacrifice the structural HCT that is original to the construction of the wall (see Figure 38)
- this retaining wall is located in the area indicated by the arrow on the plan in Figure 36.
This area had been previously repaired but the repaired failed and new repair method is
needed. The challenge of preserving the damaged areas of the house where the HCT is
found is an opportunity for preservationists to not only collaborate on the topic, but to
also find solutions relevant to other future projects.

WHAT WAS LEARNED: The preservation of the HCT at the Hollyhock House is an
ongoing learning tool. At the moment, there is no definitive solution to the dilemma of
preserving the HCT walls. The method used to preserve the HCT of the garage is one
solution and a solution that can be easily replicated. This case study reinforces the idea
that HCT, when it is such an integral part of the historic fabric, should be preserved
where possible.

90
Case Study No. 5: The Ambassador Hotel
Los Angeles, CA

Restoration Project Team:
Owner: Los Angeles Unified School District
Architect: None
Historic Architect: None
Engineer: Nabih Youssef and Associates (consultant)

BRIEF HISTORY: The Ambassador Hotel, designed by architect Myron Hunt in 1921,
was considered one of Los Angeles’ most elite hotels. Its history includes visits from
Hollywood celebrities to United States Presidents. One of its most noted events was the
assassination of Robert F. Kennedy. The hotel was sited on 23.7 acres of land just off
Wilshire Boulevard in the historic Wilshire Center district. Designed in the popular
Mediterranean style, the Ambassador Hotel originally had a salmon-color exterior with
Figure 39: Historic photo of the Ambassador Hotel. Source: University of Southern California
Digital Library Photo Collection, “Palm tree in front of the Ambassador Hotel,” Record ID: chs-
m247, date unknown.
91
red clay tile roofs. As mentioned previously, Myron Hunt used HCT in a number of his
buildings, and the Ambassador Hotel is no exception. The HCT in the Ambassador was
used as infill between the structural frames. The exterior stucco was applied directly to
the HCT walls like at Swan Hall. The hotel was “H” shaped with four separate wings
flanked the central core of the hotel. As well as the main hotel, there were a number of
separate bungalow buildings situated across the property. The property was never
formally designated as an Historic-Cultural Monument of the city of Los Angeles, though
it was found eligible for the National Register of Historic Places in a 1977 survey.
113

In 1987, the hotel closed and the property then had a succession of owners through the
years. Eventually the property was owned by the Los Angeles Unified School District,
and the hotel was considered for use as part of a school that was to be built on the site.
The Los Angeles Conservancy battled to save the hotel for over twenty years.

WHY THIS CASE STUDY WAS CHOSEN: In its efforts to save the hotel and provide
the much needed school, the Los Angeles Conservancy made the case that the hotel was
structurally stable and able to be converted into a high school. However, those opposed to
the idea of restoring and retrofitting the hotel, claimed it would never be able to be

113
The Los Angeles Conservancy’s Ambassador Hotel Design Charette held on June 12, 2001, page
number unknown. Copy of this document can be found at the Conservancy’s office in Los Angeles, CA.

92
brought up to the strict codes set forth by the Field Act, in large part due to the extensive
use of the HCT throughout the building.
114

In the case of the Ambassador Hotel, the reality is that HCT was the major reason the
hotel could not be saved. The HCT was such an integral part of both the exterior stucco
walls and the interior partition walls, making it difficult to remove it. Similarly to Swan
Hall, the exterior stucco was applied directly the HCT walls of the hotel. Unlike Swan
Hall the walls were not double width, making it challenging to save the original historic

114
The Field Act was addressed in detail in chapter 3. It should be noted that the Field Act only applies to
public schools. There are a number of private schools throughout California that have successfully
converted historic buildings into thriving, beautiful campuses. Though it is easier for private schools to
convert historic buildings because they do not have to abide by the Field Act, there are also a few public
schools that have accomplished this. One example in Los Angeles is the Science Center School and Amgen
Center for Science Learning, which is a former National Guard Armory.

Figure 40: Ariel view of the Ambassador Hotel illustrates 'H' shape of structure. Source: The Urban Partners
LLC website: www.urbanpartnersllc.com, accessed September 10, 2012.
93
fabric of the building and reinforce the HCT at the same time. However, studies were
done by a number of architects and engineers who proposed design options for structural
reinforcing that would save the HCT.
115
The strict requirements of the Field Act make it
extremely difficult to justify structural stabilization of a building sufficient enough to be
used as a public school. In a report written in 2000 titled “ New Schools, Better
Neighborhoods; LAUSD & The Ambassador Hotel: The Promise, The Problem, & A
Plan,” there is mention of what needed to be done to structurally upgrade the building in
order to be used as a school. This section of the report discusses the numerous
alternatives proposed so that the existing Ambassador Hotel could remain and be
incorporated into the new high school.
Two of the options involve the use of the building or a portion of the building as
high school classrooms. The use of any portion of the building as a school
presents specific structural issues, which are not generally involved with other
uses. The Office of State Architect (OSA) governs the design of all schools in the
State of California. The strict design requirements do not generally allow for
alternative design concepts. Such structural changes include the elimination of
one column at the center of each classroom and design modifications to make the
hollow clay tile of the existing exterior wall acceptable (providing an anchoring
system for the hollow clay tile walls and replacing tile infill with more suitable
material). The study recommends the use of shear walls as the most cost effective

115
Nabih Youssef and Associates was one of the structural engineers that provided recommendations on
how to reinforce the HCT of the existing hotel.
94
retrofit method… The reuse study estimates that the cost of seismic retrofit work
would be $5.3 million, or $12.50 per square foot.
116

This statement reinforced the notion that in order to reinforce the existing hotel and bring
it up to the code requirements of the Field Act, not only would the cost be high, but much
of the historic fabric would have to be encapsulated or replaced with new materials,
increasing project costs. The hotel was subsequently demolished and a new school
structure was built.

WHAT WAS LEARNED: The battle to save the historic Ambassador Hotel proves that
reconciling historic buildings with our modern day construction requirements can make
the reuse of historic buildings challenging, and in some cases impossible. In the case of
the Ambassador Hotel, to put it simply, the future use of the building was a public school
and the strict code requirements of the Field Act rendered the rehabilitation unfeasible. If
the proposed reuse of the Ambassador Hotel were potentially anything else, the chance of
saving the original building would have been much greater. This case study demonstrates
that it isn’t always only the techniques of material conservation that make preservation
challenging for even the most talented preservationists.

116
New Schools, Better Neighborhoods, “ New Schools, Better Neighborhoods; LAUSD & The
Ambassador Hotel: The Promise, The Problem, & A Plan” dated June 1, 2000, page number unknown. This
document can be found at the Los Angeles Conservancy’s office in Los Angeles, CA.
95
Conclusion
The prevalent use of HCT in Southern California during one of its most significant
periods of growth poses a dilemma for the preservation community. As illustrated in this
thesis, HCT was originally designed to protect structures from fire, but evolved over time
into other applications. A number of earthquakes throughout California made it clear
HCT lacks the structural capabilities needed to resist such seismic events. Eventually
building codes throughout California made it impossible to construct new structures out
of this archaic material. Additionally, newer more cost effective and efficient building
materials took the place of HCT in the construction industry.

Further research can still be done on the topic of HCT – beyond history of the material,
there is still a great deal to be learned. The majority of the research for this thesis focused
in on the west coast and Southern California. Further research can be done on
manufacturers across the United States as well as how HCT is preserved and treated in
other parts of the country. Also of interest would be a more in-depth analysis of a specific
case that would include a cost comparison of the removal verses the preservation of HCT.

One of the most problematic and common uses of HCT is as an interior partition wall. In
historic buildings throughout Southern California, the HCT interior partition wall is
typically demolished, especially in situations where such walls are in corridors or areas
not adjacent to any character defining features. In addition to the case studies provided in
96
this thesis, an analysis addressing the specific challenges of preserving interior HCT
partition walls in both corridors and public spaces such as lobbies would be very
beneficial.

Preservationists attempting to preserve structures where HCT is an integral part of the
historic fabric are challenged by arguments of cost and life/safety verses the value of such
archaic materials. However, in examining a series of case studies, it is clear that the
preservation of HCT is often possible and there are creative ways to do so.
Preservationists can use this as a resource in the future when advocating for the
preservation of potentially difficult or troublesome historic building materials like HCT.

97
Bibliography
Alden Estes, Lewis. Earthquake-Proof Construction; A Discussion of the Effect of Earthquakes on Building
Construction with Special Reference to Structures of Reinforced Concrete. Detroit: Trussed Concrete Steel
Company, 1911.

California State Mining Bureau, Resources of Los Angeles County, Orange County, and Riverside County.
San Francisco, 1916.

Caughie, K. Casey. “Shaking up Historic Buildings: Seismic Renovation at the Suzzallo Library,
University of Washington,” APT Bulletin, Vol. 34, No 2/3 (2003), 71-74.

Clay Products Institute of California, Earthquake and Building Construction: A Review of Authoritative
Engineering Data and Records of Experience, Los Angeles: Clay Products Institute of California, 1929.

Cosgrove, J. J. Hollow Tile Construction. New York: U.P.C. Book Company, 1921.

“Current Price of Common Building Brick Six Inch Drain Tile and Hollow Building Tile,” Brick and Clay
Record 60, no. 1 (Jan. 1922).

Davis, W. M. “The Long Beach Earthquake,” Geographical Review, Vol. 24, No. 1 (JAN 1934) 1-11.

Department of Commerce; Bureau of Standards, Circular of the Bureau of Standards, U.S. Government
Master Specification Tiles, Hollow, Clay, Load-bearing Wall, No. 507, August 10, 1927.

Department of Commerce; Bureau of Standards, Circular of the Bureau of Standards, U.S. Government
Master Specification Tiles, Hollow, Clay, Fireproofing, Partition, and Furring, No. 508, August 10, 1927.

Escherich, Susan M. “Gypsum Block and Tile”, in Twentieth Century Building Materials; History and
Conservation, ed. Thomas C. Jester. McGraw-Hill Companies, 1995, pg 162-167.

Flanagan, Roger D.. 1994. Behavior of Structural Clay Tile Infilled Frames. Phd. Diss., University of
Tennessee, Knoxville. In ProQuest Dissertations and Theses,
http://proquest.umi.com/pqdweb?did=741829701&sid=2&Fmt=2&clientId=5239&RQT=309&VName=P
QD. (accessed Jan. 19, 2011).

Forsyth, Michael, ed. Structures and Construction on Historic Building Conservation. Oxford, UK:
Blackwell Publishing, 2007.

98
Friedman, Donald. Historical Building Construction: Design, Materials & Technology, 2
nd
ed. New York:
W. W. Norton & Company, 2010.

“Glad Day Now For Occidental: Buildings on New Campus to be Dedicated,” Los Angeles Times, March
26, 1914.

Gould, Carol. “Masonite: Versatile Modern Material for Baths, Basements, Bus Stations, and Beyond,”
APT Bulletin Vol. 28, No. 2/3 (1997), pg 64-70.

Gould, Carol S., Kimberly A. Konrad, Kathleen Catalano Milley, and Rebecca Gallagher. “Fiberboard”, in
Twentieth Century Building Materials; History and Conservation, ed. Thomas C. Jester. McGraw-Hill
Companies, 1995, pg 120 – 125.

Green, Melvyn and Anne L. Watson. “Building Codes: Evaluating Buildings in Seismic Zones,” APT
Bulletin, Vol. 20, No. 2 (1988) 13-17.

Hoeppner, E. A., “Modern Fireproofing,” Fireproof Magazine, April 1903, pg 20 – 26.

Hollow Building Tile Association, The. Handbook of Hollow Building Tile Construction, Publication No.
1, Serial No. 33, May 1921. Chicago: The Hollow Building Tile Association, 1921.

Hollow Building Tile Association, The, Handbook of Hollow Building Tile Construction, Chicago: The
Hollow Building Tile Association, 1921.

Johnson, E. V. “Fireproof Tile Grain Elevator.” Fireproof Magazine, July 1902, 29-23.

Kaplan, David and Pam O’Connor, Kaplan Chen Kaplan Architects. “Occidental College, Swan Hall
Rehabilitation and Addition: Historic Resource Impact Report,” dated September 20, 2010.

Konrad, Kimberly A. and Michael A. Tomlan. “Gypsum Board”, in Twentieth Century Building Materials;
History and Conservation, ed. Thomas C. Jester. McGraw-Hill Companies, 1995, pg 269 – 271.

Langenbach, Randolph. “Bricks, Mortar, and Earthquakes: Historic Preservation vs. Earthquake Safety,”
APT Bulletin, Vol. 21, No. ¾ (1989) 30-43.

Larson, Gerald R. and Roula Mouroudellis Geraniotis. “Toward a Better Understanding of the Evolution of
the Iron Skeleton Frame in Chicago,” Journal of the Society of Architectural Historians 46, no 1 (March
1987): 39-48.

99
Louis, L. R., “Hollow Tile Floor Construction – History and Present Status,” The Western Society of
Engineers 34, no. 5 (April 1929): 299-304.

LSA Associates, Inc and Chattel Architecture, Planning and Preservation with contributions by CK Arts,
Melvyn Green and Associates, Smith-Emery Laboratories, Independent Waterproofing, Addison Pools and
Cumming Corporation. Supplemental Historic Structure Report; Hollyhock House, City of Los Angeles.
October 2009, can be found at: http://projectrestore.lacity.org/html/projects/project04_doc.htm.

McElwain, James R. “Los Angeles’s Division 88: Consequences of Government-Mandated Rehabilitation,”
APT Bulletin, Vol. 24, No. 1/2 (1992), pp 21-27.

Minton, Roy H., E. M., “Notes on a New Style of Hollow Building Block,” Brick and Clay Record,
September 1905, 86-88.

Parks, Sharon C., “Respecting Significance and Keeping Integrity: Approaches to Rehabilitation,” APT
Bulletin Vol. 37, No. 4 (2006), pg 13-21.

Paulson, Conrad. “Structural Clay Tile”, in Twentieth Century Building Materials; History and
Conservation, ed. Thomas C. Jester. McGraw-Hill Companies: 1995.

Pioneer Fire-Proof Construction Company, Patentees, Manufacturers, and Contractors, Every Description
of Hollow, Solid and Porous Tile for Fire-Proofing Buildings. Chicago: June 1888.

Plummer, Harry C. Brick and Tile Engineering; Handbook of Design. Washington, DC: Structural Clay
Products Institute, 1950.

Ritchie, T. “Notes on the History of Hollow Masonry Walls,” Bulletin of the Association for Preservation
Technology, Vol. 5, No. 4, (1973) 40-49.

Rabun, J. Stanley, Structural Analysis of Historic Buildings. New York: John Wiley and Sons, Inc, 2000.

Simpson, Pamela H. “Concrete Block”, in Twentieth Century Building Materials; History and
Conservation, ed. Thomas C. Jester. McGraw-Hill Companies, 1995, pg 80-85.

State of California, Department of Parks and Recreation, Primary Record form for the Anaheim Citrus
Packing House; recorded by Micky Caldwell on November 10
th
, 1999.

State of California, Seismic Safety Commission, Alfred E. Alquist. The Field Act and Public School
Construction: A 2007 Perspective, Sacramento: February 2007.

100
Tunick, Susan. “The Evolution of Terra Cotta: Glazing New Trails,” APT Bulletin, Vol. 32, No. 4 (2001) 3-
8.

Wells, Jeremy C., “History of Structural Hollow Clay Tile in the United States,” Construction History 22
(2007): 27- 46.

Wermiel, Sara E. “Heavy Timber Construction in Late-Nineteenth Century Commercial and Industrial
Buildings,” APT Bulletin 35, no 1 (2004): 55-60.

Wermiel, Sara E. The Fireproof Building; Technology and Public Safety in the Nineteenth-Century
American City. London: The John Hopkins University Press, 2000.

White, Charles E., Jr. Hollow Tile Construction, ed. W.S. Lowndes, Ph. B. Philadelphia: David McKay
Company, 1924.

Wight, Peter B., “Origin and History of Hollow Tile Fire-Proof Floor Construction,” The Brickbuilder 6,
(1897): 53.

Wight, Peter B. “The Fireproofing of High Office Building.” Fireproof Magazine, July 1902, 44-49.

Woodcock, David G., “Encouraging Excellence While Maintaining Standards: An Ongoing Discussion,”
APT Bulletin Vol. 37, No. 4 (2006), pg 43-48.

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Asset Metadata

Creator Cimmarusti, Loretta Ann Kathryn (author)

Core Title Maintaining historic integrity and solving a rehabilitation dilemma: the history of hollow clay tile and an argument for its preservation

School School of Architecture

Degree Master of Historic Preservation

Degree Program Historic Preservation

Publication Date 10/16/2012

Defense Date 09/13/2012

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag clay tile,HCT,hollow,hollow tile,OAI-PMH Harvest,preservation,tile

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Sandmeier, Trudi (committee chair), Green, Melvyn (committee member), Lesak, John (committee member)

Creator Email lacimm84@gmail.com

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c3-104591

Unique identifier UC11288355

Identifier usctheses-c3-104591 (legacy record id)

Legacy Identifier etd-Cimmarusti-1251.pdf

Dmrecord 104591

Document Type Thesis

Rights Cimmarusti, Loretta Ann Kathryn

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

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