The picture shows a test pit at an old warehouse in the Bronx. It was built around 1890 – hence the wood columns – and we were trying to figure out what the foundations are.
There’s a relatively recent concrete slab on grade in the cellar, but the interesting thing is the layer of brick below it, which can be clearly seen on the right side of the test pit and a little less clearly on the left side. The test pits showed that layer of brick is continuous across the entire area and is pretty clearly the original flooring.
It’s easy to forget how limited the choices for designers and builders were 130 years ago. They had brick and terra cotta, stone, wood, cast and wrought iron, steel, and unreinforced concrete. The concrete they had was of variable quality, and therefore not especially reliable, and not very strong. Structural choices and, to a large degree, architectural choices, had to be made from that list.
Of the available materials, only the concrete and brick made the slightest bit of sense for paving on grade in the cellar of a warehouse. Unreinforced concrete tends to crack randomly, while brick paving cracks at the joints and can be easily replaced in small areas if needed. So the choice of brick for the original floor was a rational response to the requirements and the available solutions.
To understand old designs, you have to get into the mind-set of the original designers. They were generally smart people working with a limited number of choices of materials and systems and with limited analytic tools. I’m never not impressed with what they accomplished given those constraints.
