Investigation the Hard Way and the Easy Way

by Don Friedman on February 7, 2017

Pretty underside of a floor, right? Constructed about 1895…maybe the peeling paint isn’t so nice but otherwise fine. The electrical conduits do a nice job of high-lighting the curve of the floor.

The question I wanted to answer while I was there: what’s the floor system? I was almost positive¬†that there were steel beams at the bottom of each scallop and that the flat-sided thing towards the bottom of the picture was a steel girder, but what spans between the steel? It could be brick, terra cotta, or concrete; if concrete it could be bar-reinforced, mesh-reinforced, unreinforced, or one of the bizarre systems.

My client didn’t yet own the building, so I couldn’t ask for destructive probes. In the end, I simply walked the entire 10,000 square feet of the cellar looking for a hole or other defect that would allow me to see inside the floor. When I was almost done, I found this:

That’s a hole, just right of the picture’s center, that shows solid reddish masonry. In other words, it appears to be a brick arch. After walking the whole cellar, I had evidence that got me to maybe 75% certainty. Then I walked into the last room on the level, the boiler room:

And, hey! The bottom flanges of the steel beams are exposed, and he brick is clearly visible in the vaults. If I walked in to this room first – literally a matter of starting my investigation by sweeping counter-clockwise rather than clockwise – I would have had 100% certainty in a minute. Luck strikes again.

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