Before Gyp Board

by Don Friedman on January 25, 2016

The picture below is in a fairly typical “pre-war” apartment house in Manhattan, after interior demolition has been completed for an apartment renovation. The building has a steel frame, concrete floor slabs, and a brick curtain wall. (Two concrete-encased steel beams are visible at the top of the photo.)

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The partitions shown are a fire stair (the part on the left) and the stair vestibule for this apartment (the part on the right). The stair enclosure is terra-cotta block covered with plaster and is good for at least a three-hour fire rating. The vestibule is constructed of gypsum block. Gypsum was used for the same reason we would use it today – it’s an easy way to get a good fire rating – but it was used in the older form of ashlar blocks instead of sheets.

The brand name “GYPSTEEL” is embossed on the blocks. This was a form of wire-reinforced gypsum construction that included lightweight plank similar in function to the thinner types of precast concrete plank we use today.

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