If we recall the hurried rush in which Chicago’s buildings were rebuilt after the 1871 fire, incorporating green lumber brought into the city straight from the forests in Michigan and Wisconsin, that was in many buildings made “fireproof” with a coating of plaster, we should then expect a corresponding onset of dry-rot in this wood within a few years. The timing of the development of Drake and Wight’s column could not have been more propitious, for the summer of 1876 marked just such a crisis in Chicago of considerable proportions. While the use of green lumber by itself posed no direct problem, however, when one hermetically seals such wood with paint, varnish, or plaster, fungi within the wood that can chemically deteriorate the wood cells, are allowed to multiply and attack the wood because of the moisture within the wood’s cells that the fungi needs to survive, is not allowed to naturally escape the piece of wood, thereby setting off the necessary chemical reaction. The cheapest way in which to fireproof wood immediately after the fire was to encase the wood members in a thick coat of lath and plaster. But this assumed the wood had been at least air-dried. This construction had been somewhat promoted at a nationwide level, beginning with the 1871 A.I.A. National Convention following the Chicago fire. Only four years after the fire, however, a problem began to manifest itself in the mysterious failures of all types of post-fire buildings. This was not caused by what some historians have labeled “post-fire flimsy construction,” but by the formation of dry rot in the hermetically sealed wood. The plaster-encased wood had been an attempt to build not only a better building than had existed before the fire, but also one that was fireproofed. While the technique was less expensive than Johnson’s system of terra cotta floor tiles, it still required more capital than pre-fire construction and therefore, cannot be construed as either inferior or “flimsy.” This was not just limited to Chicago, but because of the greater number of buildings constructed there after the fire, was a problem of greater magnitude there than in other U.S. cities.
In the summer of 1876, two of Chicago’s larger, post-fire buildings were in the process of having their entire interior structures replaced because of dry-rot. Field and Leiter’s huge new five-story wholesale store at the northeast corner of Madison and Market (N. Wacker) had been considered a miracle when it was completed, for it took only 100 days to construct it. Green timber posts had been used throughout the six floors, including the basement. These were then finished with varnish and several layers of paint, hermetically sealing the new wood and assuring the onset of dry-rot. During 1876 the company was forced to replace the rotted members as quickly as they were discovered, but wooden posts continued to be used.
Field and Leiter’s major competitor, J.V. Farwell and Co. suffered no less in the newest section of their large post-fire building at the northeast corner of Monroe and Market (S. Wacker). Here the wooden columns and girders had been encased in plaster as an attempt to fireproof the structure. The girders had so quickly decayed within three years that the posts, which were not continuous but beared instead upon the tops of the girders, were able to crush through the rotted girders, causing isolated failures among the floors, sometimes without warning. The entire interior wood structure of the new addition was replaced in 1876 with continuous iron columns that supported timber girders.
Throughout 1877, buildings across the country, especially in Chicago, were collapsing without warning, causing much concern among owners as well as the general public. An editorial in The American Architect decried the situation:
“In the propositions for casing wooden beams in stucco and the like, we have not much faith. If the wood is embedded in them we invite dry-rot, and our floors are likely to come down some day as did certain warehouse floors in New York lately, without warning. Whether imbedded or not we know of but one available material to cover them, –terra-cotta– which is not friable under heat, and which might not be expected to shatter and fall away if exposed to a fire hot enough and long-continued enough to endanger an iron beam; and we doubt if even terra-cotta could be made secure under such circumstances. All such materials make floors extremely heavy, and so are likely to increase the cost of them to the degree that it seems better to go farther in search of a less equivocal security.”
The editorial also suggested a major shift in the prevalent fireproofing strategy:
“It is not so easy, it is true, to make our houses impregnable against such fires as swept Boston and Chicago; but if our city laws insisted on the fire-proof building that can be done, such fires would never occur. Where no building burns from within, we may be sure that none will take fire from without.”
In the face of the emphasis on strong exterior masonry walls and solid roofs, this shift of emphasis once again to the interior is extremely significant. Before the heavy fireproof masonry walls and window shutters could be stripped from a highrise building and replaced with a light-weight curtain wall of terra cotta and glass, a city building’s stock would have had to have been made relatively incombustible, making the extensive exterior protection unnecessary. This was to be accomplished only by the total elimination of wood structures, which in Chicago was still eight long years beyond the editorial.
Undoubtedly, the dry rot problem had thrust Drake and Wight’s fireproofed iron column into the limelight, as wood columns were no longer viewed as more acceptable than iron columns since the cheap coating of plaster as fireproofing was no longer viable. The “Chicago Correspondent” of The American Architect was quick to report on the problem:
“It may be of interest to note, with reference to the prevalence of dry-rot in a building only five years old, that the internal construction of the old building was of iron columns and double girders…This system of floor construction in wide stores has been extensively practised in this city, and has failed in many instances through the prevalence of dry-rot…The extent of decay in timber has doubtless been aggravated by the extensive use of green timber during the days of hurried building. Altogether it is a strong argument in favor of the use of iron, which is now cheaper than ever before, and within the reach of many who could not have employed it a few years ago.”
(Note that the lengthy depression of 1873-9 had begun to affect the price of materials, especially iron which made it even more competitive with wood.)
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The Architecture Professor 