Historic Structural Detail: Some Artifacts Are Bigger Than Others

by Don Friedman on February 19, 2016

In most alteration projects, the first stage of construction is demolition of the interior finishes. When that work is done, we often find conditions that we did not know existed and would not have known with the demolition. Sometimes those conditions affect our work, sometimes they are simply artifacts showing us some information about how the building is put together.

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What is that thing? And, of course, we were asked if it can be removed. This apartment is at a setback floor in a 1920s high-rise, and there’s a terrace beyond the visible wall. The terrace, interestingly enough, is elevated above the interior floor, so that thing could be continuing out to the edge of the building. The answer is that it’s a column transfer. The column above the transfer is just inside the wall, and this thing is a heavy built-up riveted girder. Because the girder is much deeper than the ordinary floor framing, the original designers had the option of having a thing bumping down from the ceiling on the floor below or this thing bumping up here; they chose to have it go up because it was originally hidden inside some closet spaces.

Why is the thing so big and so ugly? Because there was no practical welding technology for building use at the time. Making connections with fasteners – either rivets in the 1920s or bolts today – requires that the elements being fastened be in at least roughly parallel planes. So a lot of angles had to be used to connect elements that are not in parallel planes, and a lot of small plates had to be used as filler pieces to get parallel planes to align as the same plane, and so on.

In other words it all makes perfect sense given the steel technology of the era. We just need to get our heads into the past to understand it.

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