Looking Up: An Introduction to Steel Frame Structures.

We’ve talked a lot about Burnham and how he struggled with developing the “Chicago School of Architecture” because he was so stuck in the architecture of the past.

You may have heard the term before, The “Chicago School”, but what does it mean? What do I mean when I say that Sullivan was building in a whole new way? What was going on here that wasn’t going on in New York or Boston?

Well it all started with the fire of 1871. Previous to the fire, most of the buildings were cast iron or wood. When the fire hit, 70,000 buildings burned, 300 people died. It scared the city, and new builders were told to only build fireproof buildings.

NYC and Boston weren’t nearly as scared of fire as we were, and our fear of fire led to the innovation of what is now known as “steel frame structure”. William LeBaron Jenney built the first steel framed structure building in 1885, (The Home Insurance Building. Alas, it no longer stands), meaning the skeleton of the metal frame was actually holding up the building. Previously to this, the walls bore the load of the building (known as “load bearing” buildings, imagine that). When building a load bearing structure, the walls had to get thicker as the building got higher. For example, check out the Monadnock building at 53 W. Jackson (above), designed by Daniel Burnham and John Root. The higher the building goes, the thicker its walls get. You can see how thick they are through the windows. (left) The Monadnock is still the tallest, occupied load-bearing structure in the world.


But once the skeleton could hold up the walls, the buildings could grow higher.

When Jenney built his skeleton frame, he basically hung the walls of the building onto the skeleton. Even today, the cladding of a building is called the "curtain wall", because you’re just hanging it right off the frame. We mostly used terra cotta as the cladding, because it was fireproof.

So, boom, in Chicago we’re building buildings no one had ever seen before...Skyscrapers. With the invention of the elevator and the revolving door (which regulated wind and heat in the building), the buildings got higher and higher. Initially, people were generally afraid of these higher buildings, so when you look at historic Chicago skyscrapers, they tend to look boxy, and big, and sturdy.

Check out the Marquette building designed by Holabird and Roche in 1895 at 140 S. Dearborn, notice how dark and heavy it is. (left)

Next week we’ll learn how Louis Sullivan managed to influence almost the entire city (including Burnham himself) with his plan to build these new-fangled skyscrapers.