3.20. THE RETURN TO MASONRY BEARING WALLS: “BOXED” CONSTRUCTION
But Wight’s system of fireproofing was applicable only to an iron skeleton frame in the interior of a building. This location was not exposed to the extreme temperature fluctuations that a building’s exterior experienced during the annual weather cycle in Chicago or New York (or Minneapolis!). In addition, before architects could start putting their exteriors on a similar diet, those heavy masonry exterior walls were still needed for fire protection until the majority of a city’s building inventory was made fireproof with the new technology. The actions by the National Board of Underwriters taken after the Chicago fire of July 14, 1874, in addition to forcing changes to be made in the manner in which the interiors of buildings were constructed, would also force architects during the second half of the 1870s to reconsider how to design and construct the exteriors of buildings. The new codes adopted by the insurance companies reflected the views of a growing number of experts that no matter what was done to the interior of a building that contained combustible materials, if the exterior was not designed properly, the building would still burn if exposed to the fire of an adjacent building. Therefore, the new codes required the use of solid exterior walls.
The bottomline following the successful test on November 15, 1881, was that architects would still be reliant on masonry exteriors for the immediate future. That meant that the early skyscrapers would comprise of “boxed” construction: a fireproofed iron skeleton frame erected within a masonry box. That box could be a solid brick wall with holes cut into it (Monadnock) or it could be comprised of brick piers and spandrels (Shillito’s).
In Section 1.11 I reviewed Jenney’s use of iron posts set at the interior face of the masonry piers (in compliance with the building code) in one of the two streetfronts in the First Leiter Building as the first timid step in the evolution of the skyscraper’s exterior from masonry wall to iron skeleton framing, but no one, including Jenney, followed up on this detail during the following five years. So just what were the limitations of the exterior masonry bearing wall that challenged architects in the design of the first skyscrapers?
3.21. BRICK VS. STONE?
The emphasis upon the use of brick, to the exclusion of stone, was due to the observed poor behavior of stone veneers and walls in both the Chicago and Boston fires. This attitude was eventually codified by a series of experiments conducted in 1880 on the response that various building stones had exhibited when exposed to fire, by Dr. Cutting, the State Geologist of Vermont. The results, published later in American Architect, had substantiated Peter B. Wight’s earlier claim:
“He declares, in substance, that no known natural stone deserves the name fire-proof. Conglomerates and slates have “no capability” of standing heat; granite is injured beyond cheap or easy repair by even so mild a heat as that which melts lead; sandstones, including the variety called brownstone in this city, are better, and limestone and marbles are perhaps the best in this respect. But even they are injured by continuous heat of 900 degrees, and at 1,200 are changed into quicklime. Therefore it would seem that no stone buildings are fire-proof, and some of them, Dr. Cutting even says, are as much damaged by fire as wooden structures are. Brick, on the contrary, is usually uninjured, and is often rather improved by heat until it is melted. But as most brick buildings are trimmed with iron or stone, the damage is often considerable, even when the walls stand. . . The search for an ideal building material is not hopeless, but it must be prosecuted rather by the maker than by the quarrier of stone.”
As stone had displaced cast iron in the 1860s, pressed brick and Loring’s terra cotta were beginning to be favored over stone in the 1870s as the material of choice for the exterior of a building. The acceptance of brick as an exterior material for commercial buildings was furthered by the stylistic abandonment, coming on the footsteps of the French defeat by the Prussians, of the Second Empire’s Neo-Baroque use of “Classical” elements in favor of either the more fashionable British Gothic revival, especially the Queen Anne, or the German revival of the Romanesque or rundbogenstil (round-arched style), both of which incorporated brick in a building’s exterior. However, a preference for brick exteriors that had even preceded these early essays had been the Quaker tradition of Philadelphia’s red brick commercial brick fronts of the 1850s (see Vol. 2, Chap. 5), and the numerous red brick buildings erected after the end of the Civil War in Washington D.C. designed by German-immigrant architect Adolf Cluss.
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