Historic Structural Detail: The Ghost of a Barrel

by Don Friedman on March 30, 2016

Not every detail is important today, but they all exist for a reason. How did concrete contractors create round columns before reusable steel forms?

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The portion of this 1910s column at the top of the photo is still covered with plaster. The plaster has been removed at the bottom, showing the board marks. The vertical lines are sharp corners where small amounts of cement and sand squeezed between the boards. The boards were narrow – 2 inches and less – unlike the boards used to form the slabs and beams. The completed column form-work must have greatly resembled a barrel: a circle of narrow wood boards held together by several steel hoops.

Of course, when I evaluate the strength and condition of this column now, close to 100 years after it was built, how the forms were created is not relevant. But to understand the building thoroughly, it helps for me to understand the original system of construction. You never know, in advance, what detail will help guide you.

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