8.17. “NO BEAM, NO FRAME:” IT WAS NOT THE FIRST USE OF AN IRON SKELETON FRAME

Jenney, Home Insurance Building. Surviving fragment of the iron structure in the Museum of Science and Industry. Note the stub spandrel beam (at the left of the column) that the Field Committee chose to include in the fragment left for history. As this beam was located in only three of the eight floors that were skeleton-framed, the committee attempted to mislead future historians about the true nature of Jenney’s structure, (Author’s collection)

I have now shown you a litany of tall buildings in which some aspect of iron skeleton framing had been incorporated in their exteriors before Jenney first experimented with it in April 1884 for the Home Insurance Building. (There is no issue about interior iron skeleton framing in 1884, it was ubiquitous by then.)  The independent iron frame with a masonry curtain wall had been in service in the U.S. for some twenty-five years following Bogardus’ New York shot tower of 1855.   As far as I have been able to determine, George Post in New York had been the first American to use iron framing in an exterior wall since the urban conflagrations of Chicago and Boston in his detailing of the exterior lightcourts in the New York Produce Exchange (1880), and the Mills Building (1881), and just maybe even before the fires in in the Equitable Building (1867). These experiments were soon followed in Chicago by Root in his lightcourts for the Insurance Exchange, Phoenix Building, and also, of course, The Rookery (see an upcoming post).

So are we then looking for the first building whose exterior structure was solely iron framed?  If so, that leaves the Home Insurance Building out of the running because it still had two exterior loadbearing masonry party walls, in addition to the first two stories of its streetfronts having been solid masonry.  It will be a cautious step-by-step process in replacing the tried-and-true (and very stiff with regards to wind loads) bearing wall in the exterior of building with the iron frame.  The first all iron-framed tall building will be erected in 1888, and we’ll try to ascertain which building and architect/engineer deserves to be so credited when we get to that year.

Jenney, Home Insurance Building. Eighth floor plan. (Tallmadge, The Origin of the Skyscraper)

Admitting that the Home Insurance Building was neither the first skyscraper nor the first building completely framed in iron, then what “first-in-the-world” title is left for it to claim? (And why bother, other than for some civic boosterism on the part of Chicago?)  I think the best that one might argue is that it was the first use of iron skeleton framing in the exterior of a tall building in Chicago? (Remember, Post had already accomplished this in New York.)  Let’s examine this claim: that is, Jenney had used iron skeleton framing in the upper eight floors in the two street fronts.

Jenney, Home Insurance Building. Reconstruction of the structural detailing of the exterior piers. (Drawing by Deborah Cohen Heller and Maxwell Merriman)

From the evidence on record, we can conclude (please refer to my 1987 JSAH article for a more detailed explanation) from at least eight points that Jenney’s loosely-bolted, eight-story framework of masonry-stiffened cast iron columns and lintel pans was not entirely self-sufficient and independent of the masonry, and, therefore, does not qualify to even be called iron skeleton framing:

Jenney, Home Insurance Building. The exterior iron structure overlayed the building’s elevations, showing the lack of spandrel beams in Floors 5, 7, 8, and 10. (David Burwinkel)

-First, there were no spandrel beams at floors 5, 7, 8, and 10.  By definition, a frame is a rigid assembly of columns and beams at each floor (unless one is speaking about a megaframe, that in 1884 was in the distant future…);

Jenney, Home Insurance Building. Section and elevation of structural iron members in the exterior, showing the location of the transfer beams at Floors 4, 6, 9, and roof. It is more important, however, to understand that there were no spandrel beams in Floors 5, 7, 8, and 10. (Jensen & Halstead, Ltd., Chicago)

Second, he did not initially refer to the masonry as a covering, but always stated that he had embedded the iron column within the masonry pier in order to reduce the size of the piers and, thereby, maximize the amount of daylight entering the interior;

Jenney, Demolition of the Home Insurance Building, 1931. (Tallmadge, The Origin of the Skyscraper)

Third, unlike a skeleton frame, Jenney had filled his iron columns with concrete, which is completely unnecessary in a skeletal-framed building (with the exception of contemporary composite structures);

-Fourth, the lintel pans were not one continuous piece of iron that spanned from column to column (therefore, they were not a “beam”) but comprised of two pieces, not mechanically connected, that spanned only from a column shelf to the intermediate mullion, thereby offering no rigidity to the structural bay whatsoever; 

– Fifth, the lintel pans were also not bolted to the columns, so rigidity of the mullion/lintel assembly was gained through the masonry in the spandrel wall;

-Sixth, the exterior brick facing of the piers, whose thickness increased to 12 inches at the corner and entrance piers, was not supported on the iron column at any point, thus it was continuously bearing for eight stories from the granite piers. (remember that Jenney had notched the pans so that the facebrick could run continuous without any connection to the spandrels in an attempt to minimize cracking in the facebrick should the spandrel rotate caused by differential settlement).  In fact, Jenney had gone so far as to specify a very conservative technique of bricklaying for the piers’ face brick to achieve a stronger-than-usual assembly to keep the cross section of the masonry piers to a minimum.  Selected hard brick was used with a strong cement, not lime, mortar and was laid up in very tight, solidly packed joints.  This would have been entirely unnecessary if Jenney was supporting the face brick on the iron frame at each floor. The importance of this point is that the concept of the iron frame is to completely support its masonry enclosure, which it definitely did not do in this building;

-Seventh, as the columns typically extended laterally unbraced by iron beams for two stories (the spacing of the transfer beams that supported the mullions), and in the middle of the building for three stories, the columns more typically relied solely on the rigidity of the spandrel masonry interacting with the masonry pier to stabilize the connection against lateral loads and to brace the columns at each floor against buckling;

-Eighth, and finally, the iron frame with its loosely bolted and clamped connections could not have resisted any wind loads.  

What I have tried to show is that Jenney’s detailing was consistent with what he had originally claimed was his objective: he had embedded the iron column within the masonry pier that then allowed him to reduce the size of the masonry piers’ cross-sections.  Jenney’s structure in the Home Insurance Building did not generate much contemporary attention or acclaim in the U.S., or for that matter, even in Chicago, during its construction nor immediately following its completion. Was there any reason for such construction to have done so?  Most likely it was viewed by Chicago’s architects and builders as an eccentric curiosity because I am not aware of any Chicago architect that employed Jenney’s details in any building in Chicago.  The Home Insurance Building was simply just one of a handful of skyscrapers that were under construction in Chicago during 1884. 

Solon Spenser Beman, Pullman Palace Car Building, Chicago, SW corner of Michigan and Adams, 1883. (J.W. Taylor: Chicago Historical Society)

Even during its construction during the latter half of 1884, Jenney himself modestly spoke of S.S. Beman’s Pullman Building as the highpoint of Chicago’s architecture.  In fact, as the Home’s iron columns began to be erected in August 1884, Inland Architect stated that the commission for the Union League Club, and not the Home Insurance Building was “the greatest compliment Mr. Jenney has yet received professionally.”   Union League Clubs had initially sprung up in the North during the Civil War and had naturally subsided once the war had been won, but by 1880 it was evident to these men who had defended their country earlier, that the country was once again inching ever closer to civil war, but this time the enemy was Socialism.  So Union League Clubs were reestablished nationwide in 1880 purposefully “to encourage and promote by moral, social, and political influence, unconditional loyalty to the Federal Government, and to defend and protect the integrity and perpetuity of this Nation.”

William Le Baron Jenney, Union League Club, Chicago, SW corner of Jackson and Custom House Place, 1884. (Chicagology.com)

If Jenney’s use of iron in the Home Insurance Building had been considered to have been of a revolutionary nature, surely it would have been quoted in any of the obituaries for Daniel Badger who died in November 1884 and was referred to as “the first person in this country to use iron on a large scale for building purposes.”  Not surprisingly, following Jenney’s description of its structural system at the 1885 A.I.A. convention in October, the Home Insurance Building and the potential of its “unique” structural system were not discussed for the next two and a half years in local or American trade magazines or conference proceedings.  In fact, nobody in 1885 had the time to worry about such esoteric points as the construction market in Chicago was still completing the erection of all those buildings that were started in 1884.  

And even once this issue had eventually ignited in the construction press, there were still those in Chicago who, not for a moment, gave the legend any creditability.  Peter B. Wight, who  outlived almost all of those in the Chicago School, was the fireproofing contractor not only for the Home Insurance Building, but also many of the other buildings that would be posited for these honors, later claimed to have introduced Jenney to Normand Patton, Chicago’s leading designer of iron structures, in order to help with the design of the iron elements planned for the Home Insurance Building: “Jenney could talk building better than any man I knew, but he knew very little how to design and construct them and depended on others.” In fact, in 1950 a former Jenney employee, Elmer C. Jensen, who had entered Jenney’s office in March 1885 as an office boy and became a partner in the firm in April 1905, had admitted that he was always puzzled over the fact that “Major Jenney never made any claim that he had originated the skyscraper principle.”

“Frame-construction,” Burnham and Root, Reliance Building, 1890, 1894. (Online)

Therefore, if one adopts the definition of a skyscraper that is a tall building constructed solely with a metal skeleton frame, one needs to ascertain what was the first such tall building erected, for it was not the Home Insurance Building.   So when did the Home Insurance Building and its structure become such a contentious issue?  There will be an event that will spark the argument, but this won’t occur until 1888.  I think the time is overdue for this urban legend to be laid to rest.  Therefore, if you hear of anyone still citing the Home Insurance’s reputation, feel free to bring this post to their attention.  I will be more than happy to debate anyone at any time about this issue.  In fact, I’ve already laid out my opening arguments above.

FURTHER READING:

Larson, Gerald, “Toward a Better Understanding of the Evolution of the Iron Skeleton Frame in Chicago,” Journal of the Society of Architectural Historians, March 1987, pp. 39-48.

Tallmadge, Theodore E. The Origin of the Skyscraper-The Report of the Field Committee. Chicago, 1934.

(If you have any questions or suggestions, please feel free to eMail me at: thearchitectureprofessor@gmail.com)

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