Workshop of the World

stories of industry in & around Philadelphia

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U.S. Gypsum, 1929-1991, demolished 2007.
South of 56th Street, west of the Schuylkill River to Eastwick Avenue, Philadelphia PA

Compiled by Sean McDonnell, Oct. 2007.

The 1920s was a period of rapid growth for the United States Gypsum Company, who constructed several new facilities throughout the country.[1] In 1929, they began building a plant in southwest Philadelphia on land formerly owned by the Gulf Oil Company.

Bordered on the north by 56th St, the south by Gulf Oil, and the west by the Philadelphia and Reading Railway (which provided rail service), the plant appeared to rely on the Schuylkill River for delivery of inbound raw materials. The plant was originally configured to produce Sheetrock, the company’s name for gypsum wallboard, and gypsum block, known as Pyrobar. The company’s own Pyrobar could actually be found throughout the plant.

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Photo of a Pyrobar block, part of a wall in a room near the west end of the calcining mill building. Though due to the age of this particular structure, it is unlikely this particular block was produced at the plant.

Gypsum, chemically known as calcium sulfate, is a naturally-occurring mineral. It is such a versatile substance because it can be ground into powder , molded into the desired shape, and be returned to its original rock-like hardness simply by adding water. The gypsum is first calcined to drive off water molecules that are part of the compound, forming plaster. This plaster is mixed with water and additives to form slurry. This slurry is sandwiched between sheets of heavy paper to form the gypsum board, which is then cut to the proper shape, dried in a heater and prepared for shipping.[2]

It was a fine example of form following function in industrial architecture and design, with varying rooflines throughout the building to accommodate the different production lines. The plant most likely got by producing Pyrobar, and regular plaster, as a site plan from the Factory Mutual Fire Insurance Company shows portions of the plant were devoted to bagging and storage of empty bags. The market for gypsum board did not explode until World War II, when the need for a fast, reliable building material finally allowed Sheetrock to surpass plaster-on-lath as the preferred method for finishing home interiors.[3]

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View northward from the west bank of the Schuyklill, showing the bridge that ran from the gypsum storage building to the calcining mills. The green pipes extending towards the waterfront were likely a pneumatic materials handling system for unloading raw gypsum from ships or barges.

The sheetrock business definitely grew for the plant, as the fire insurance map shows additional manufacturing and storage space for gypsum board was added to the plant in 1951, and again in 1960. By the time the fire insurance survey was completed in 1980 by, the buildings housing the gypsum block production lines had been demolished, and went on to serve as the site for raw materials storage. Between 1986 and 1991, US Gypsum sold the plant to a company called Certified Concrete. Plant records showed little activity dated after 1993, so that is likely the year the plant closed for good. The facility loomed silently on the west bank of the Schuylkill, serving as shelter for squatters and as a playground for urban explorers and photographers, until June of 2007 when it was leveled.

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Aerial view, looking north. The large corrugated-metal structure at the center-right was originally storage for raw gypsum. The long, two-story structure to the south was the gypsum board production area. The structures to the south of the gypsum board building housed kilns and calcining mills to convert gypsum to its usable form. This location allowed the processed plaster to be delivered to the board production area, or to the block production buildings, the concrete floors of which are visible at the bottom of the picture.

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View looking southeast, up at the gypsum storage building. The concrete silos were roughly 4 stories tall, with the remaining vertical space in the building occupied by a large gantry crane with clamshell bucket to feed the conveyor and auger.

U.S. Gypsum is #51, just below "Bartram Park", west of "Schuylkill."
Franklin's Street & Business Occupancy Atlas of Philadelphia & Suburbs, 1946, detail Map No. 6.


History & Innovations of the United States Gypsum Co.

2. Drywall - How It Is Made.

Drywall - From 1916 to today.


Audio-visual history of gypsum and gypsum products.

USG Corporation website.