I’ll be giving two public lectures in the Chicago area over the next two weeks:
Northwestern University McCormick School of Engineering
“Built Like Bridges: Iron, Steel, and the Importance of Wind Bracing to the 19th Century Skyscraper”
4:00 PM, Tuesday, 13 April. Cohen Lounge, Fourth Floor, Technological Institute (2145 Sheridan Road). Free
Association for Preservation Technology, Western Great Lakes Chapter
“Buildings Without Walls – Plate Glass and the Chicago Skyscraper of the mid 1890’s”
5:30 PM, Monday, 19 April. 18 S. Wabash. $10 for non-members, free for members. 1 CEU.
A massive fire in 1898 destroyed the loft building that stood on the site of the current Ayer/McClurg Building, killing seventeen workers. It was one of several fires that year that forced code changes and forced the City to look at escape, rather than ‘fireproof construction,’ as the primary method of life safety assurance. In particular, the fire pointed out the dangers of allowing escape through elevators (one elevator operator made several trips to the affected floors, but found himself fighting desperate workers trying to overcrowd the cab), and of external fire escapes, which proved useless as they were heated to red-hot by the intensity of the fire within.
The replacement building for client Frederick Ayer thus came under special scrutiny, but Holabird & Roche also broke new ground with its facade, which took the glass expanses of the mid-1890s curtain wall buildings and compressed them on to a flat elevation that was carefully articulated into vertical piers, horizontal spandrels, and vertical mullions. All of this was rendered in a cream-colored enameled terra cotta that highlighted the difference between light solid and dark void, and particular attention was paid to reducing the widths and depths of the cladding elements, leaving the elevation a tenuous grid that left the greatest possible area for glazing between its linear members. The building’s spandrels, in particular, were less than three feet high, leaving only 30″ of ‘wall’ on the interior.
These proportions reflected the lingering low prices of plate glass and the related refinement of enameled terra cotta as a cladding device. Holabird & Roche would continue experimenting with layers of cross-grained horizontal and vertical elements surrounding large windows throughout the early 1900s, but this formula worked only as long as glass was cheap and daylight was necessary.
For a relatively cheap commercial structure, the Ayer has survived fairly well, though it lost its cornice in the 1950s and its facade has been carved up as tenants have installed insulated window glass. Its ground floor has been entirely gutted–the Exchequer now takes up half of the street level–but it’s in desperate need of a significant renovation. Probably next on the list of major Chicago skyscrapers to need one.