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

2012-10-16This 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. ❧ 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