Burnham & Root, Rialto Building. Demolition photo showing the extent of iron framing, 1941. (Chicagology.com)

While the exterior of the Insurance Exchange broke new ground in Root’s maturing aesthetic understanding, the interior construction was still locked in the past.  As was done in the Grannis Block, an interior iron cage supported wood floor joists that were “fireproofed” with terra cotta tiles. This decision must have been a bow to economics, for Burnham & Root had not only incorporated hollow tile floor arches in the Montauk Block, but they also were also experimenting at this time with improved construction techniques in the design of the Rialto Building.  As early as March 1883, it had been reported that the owners of the Rialto had engaged the services of Normand S. Patton, an architect/engineer who had become well-versed in iron construction while working in the office of the nation’s Supervising Architect in Washington, D.C.  Patton (1852-1915) had been born and grown up in Hartford, CT, earning a BA at Amherst College in 1873, prior to his move to Chicago where he found employment in Jenney’s office (roughly paralleling Sullivan’s brief employment).  In the depths of the Depression in 1876 he had moved to Washington, D.C., until he accepted the call to return to Chicago.  The time spent in Jenney’s office was well before Jenney’s design of the First Leiter Building of 1879, meaning that Patton had become experienced with iron construction after he had left Jenney.

James Bogardus, McCullough Shot Tower, New York, 1855. (Silver, Lost New York)
James Bogardus, Santa Catalina Warehouse, Havana, 1858. The brick walls are built on the iron frame. (Gayle, Bogardus)

The Inland Architect of March 1883 reported that he had been called “to Chicago to take charge of the iron construction and act as consulting engineer [with Burnham & Root] upon the [Rialto Building].”  The importance of such expertise coming to Chicago at this particular time was not lost on the Inland Architect: “Mr. Patton has enjoyed exceptional advantages in the study of iron architecture and now, upon the eve of an era of iron and fireproof construction, his accession is a valuable one to the craft in Chicago.”  The extent of the use of iron planned for the Rialto in 1883 is not known, other than its sheer size alone would have made his experience valuable to Root. 

Cast iron columns after the 1871 fire. (Kogan and Wendt, Chicago)

The importation of Patton’s experience with iron construction, however, did not mean that iron had not been utilized in Chicago’s buildings prior to his arrival in early 1883.  Far from it: in Volume One I documented James Bogardus and Daniel Badger’s development in New York of the iron skeleton frame enclosed with masonry panels. Central to this development was the invention and perfection of the cast iron front, the first use of iron skeleton framing in the exteriors of American buildings.  In Volume Two, we saw how the 1871 Chicago and 1872 Boston fires destroyed the myth of the fireproof nature of the unprotected cast iron column and beam. Then the 1874 Chicago fire had forced the nation’s fire insurance companies to pursue the complete prohibition of iron framing in buildings that resulted in Peter B. Wight’s invention of terra cotta fireproofing.  

Meanwhile, the potential threat to iron framing had not stopped architects and engineers from continuing to refine the technique of iron framing for the interiors of buildings nor from experimenting its use for very tall towers.

David Reeves, Proposed 1000’ Iron Tower for the 1876 World’s Fair, Philadelphia, 1873. (Architectural Record, April 1959)

While iron framing in the exteriors of buildings had been for all practical purposes banned, Wight’s fireproofing technique of interior iron framing was slowly adopted and successfully used in all of Chicago’s tall office buildings erected in the early 1880s.  This type of construction I labeled “boxed” construction: a masonry box was constructed around the building’s exterior within which were erected the iron columns and beams.  Windows in the brick box were detailed either as holes built into the walls or the brick box was detailed as a series of piers linked by masonry spandrels.

Burnham & Root. The Rialto (left) as an example of pier-and-spandrel detailing and the Insurance Exchange (right) showing its wall-with-windows detailing. (Hoffmann, Root)

Therefore, the independent iron frame with a masonry curtain wall had been in service in the U.S. for some twenty-five years following Bogardus’ shot tower of 1855.  George Post had led the way in New York in his detailing of the exterior lightcourts in the Equitable (1867), the New York Produce Exchange (1880), and the Mills Building (1881). Chicago did not invent iron skeleton framing. The iron frame in 1883, therefore, was not, by any means an unknown technique waiting to be “invented” as many historians have claimed; by this date it was a well-developed system of construction. 

Post, Produce Exchange, 1880. Photo of Construction showing the iron skeleton framing in the lightcourt walls. (Landau and Condit, New York)

Meanwhile in Chicago, William Le Baron Jenney in his First Leiter Building of 1879 had inserted iron sections against the interior faces of the masonry piers to take the floor loads off of the piers. Jenney’s rather ad hoc detailing, however, did not catch on nor was reused in Chicago.

Jenney, First Leiter Building, 1879. Above: Construction Detail of Masonry Spandrel and Pier. Note that the iron spandrel beams have a bearing plate that transfers their load to the masonry, not the iron pilaster. Jenney used a pair of plates to connect the webs of the spandrels at either side of the pier to gain some continuity through the joint. Below: Sectional Elevation of Ironwork in Monroe Street Facade. Note three details: first, the spandrels bear on the masonry (as detailed above); second, the iron mullions are continuous, i.e., loadbearing to the foundation; and third, there are no iron sections in the masonry piers. (Art Institute of Chicago)

Meanwhile, within a year, S.S. Beman had designed the 195’ tall Water Tower for the Town of Pullman in 1880 using 100’ long iron columns fabricated by N.S. Bouton and George Pullman’s Union Foundry and Pullman Car-Wheel Works. By this date, iron construction was being given more exposure in Chicago’s architectural press.  

S. S. Beman, Pullman Water Tower, 1880. Section, Elevation. The 100′ tall iron columns that support the 500,000 gal. tank. (Online)

Across the street from the Montauk Block, then under construction, Haverly’s Theater was being erected.  Although the exterior consisted of solid brick walls, the supports of the galleries were all iron, leading Real Estate and Building Journal in July 1881 to state: “It is possible and feasible to construct the auditorium entirely of a light iron framework, which would make it practically fireproof, and every theater should be built this way.”  

Peter B. Wight, Fireproofed wrought iron Phoenix columns in the Chicago Board of Trade Tower, 1883. (Brickbuilder, August 1897)

Then in 1883, the same company that manufactured the iron columns for the Pullman Tower, had also fabricated the 90’ high, 12-sectioned Phoenix wrought iron columns, once again fireproofed with Wight’s terra cotta casings for the Board of Trade’s great tower.  Large wrought iron columns were also used in the Board of Trade to support the iron trusses that spanned the Trading Floor: “the outside walls will be surrounded with large, full columns placed between the windows, and they will largely support the upper stories.” Patton may have played a role in the design of these iron members, for he had been brought to Chicago in early 1883 to help with the iron construction in the adjacent Rialto project, a period that parallels the design of the Board of Trade.  The first report of the large iron columns in the Board of Trade appeared in October 1883, with construction lasting from December 1883 to August 1884. The photographs below suggest that the iron columns were fireproofed by being encased in brick and stone.

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

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