Q.: We build a lot of forms for square cross-section columns with 24-inch sides. Depending on the forming details, at least half of the 48-inch-wide sheathing panels have to be cut 24 3/4 inches wide to allow for overlap at the corners. That leaves us with a lot of leftover plywood 23 1/4 inches wide. This is wasteful unless we have some smaller columns on the same job. Is there a way to reduce this waste?
A.: If you use ¾-inch chamfer strips on the corners of the columns, your carpenter can cut a 48-inch-wide piece of plywood right down the center. The strips make up the ¾-inch panel run-by needed on wrap-around column forms. The chamfer-strip approach also works well for column forms with 16-inch sides, allowing a carpenter to cut three 16-inch column sides out of one 48-inch plywood piece. For a column-form corner detail showing use of a chamfer strip, see "Forming Chamfers and Rustications," Concrete Construction, October 1998, page 853.