A Hidden Name

That’s a steel beam from the roof framing of a 1903 building, made visible by the construction of a new stair. The writing on it is the identifying information for this beam, for use by the steel erector 116 years ago. The painted designation was hidden by the terra cotta tile arch of the roof until that was cut out a few weeks ago as part of the stair construction, so this is the first time that writing has been visible since the building was built.*

The top line is “B15” which is straightforward: it’s the designation for this particular beam. There may have been more than one B15 – based on the roof layout, I’m guessing there are about two dozen of them – because that designates a specific beam size, length, and connection geometry. If there are multiple beams of the same size that are the same length (because they’re spanning between identical girders the same distance apart) and with the same connections, then they’re all going to be B15s. The erector could have put any one of them in this location and it would fit.

The second line is a statement of truth: this beam is part of the 13th tier of framing. A lot of older buildings left out the 13th floor for superstition, developers have been known to skip some floor numbers to make their buildings seem higher than they actually are, and mezzanines or other levels of floor framing may be squeezed between regularly-numbered floors. But the tiers of framing are numbered from the bottom up and reflect simply how many horizontal levels of framing there are. This building has no skipped floor numbers and no non-numbered levels, so the roof above the 12th floor is the 13th tier.

The third line is a mystery. The beam in question is too small to weigh 84 pounds per foot, so that’s not a weight marker, and it’s odd to have the beams numbered consecutively when they have more ordinary numbers like “B15.” But odd things sometimes take place.

* That might seem remarkable but it’s reasonably common. Sometimes when buildings are demolished we see signs painted on the sides of their neighbors that have been hidden for 50 or 100 years.