Length of Waring in feet. Breadth. 1 1/4 in. Breadth, 1 3/4 in. Breadth, 2 in. Breadth, 2 1/4 in. Breadth, 2 1/2 in. Breadth, 2 3/4 in. Breadth, 3 in. depth, inches. depth, inches. depth, inches. depth, inches. depth, inches. depth, inches. depth, inches. 4 2 1/4 2 1/8 2 .. ... ... ... 5 2 3/4 2 3/8 2 1/2 ... ... ... ... 6 3 3/8 3 1/4 3 2 7/8 ... ... ... 7 4 3 3/4 3 1/2 3 3/4 3 1/4 ... ... 8 4 1/2 4 1/4 4 3 7/8 3 3/4 3 5/8 3 1/2 9 5 4 3/4 4 1/2 4 3/8 4 1/2 4 1/8 4 10 5 3/4 5 3/8 5 4 7/8 4 3/4 4 5/8 4 1/2 11 6 1/4 5 7/8 5 1/2 5 3/8 5 1/4 5 1/8 5 12 6 3/4 6 1/2 6 5 7/8 5 3/4 5 3/8 5 1/4 13 7 1/2 7 6 1/2 6 1/4 6 5 7/8 5 3/4 14 8 7 1/2 7 6 3/4 6 1/2 6 3/8 6 1/4 15 8 1/2 7 7/8 7 1/2 7 3/8 7 1/4 7 6 3/4

Ceiling joists should never have very long bearings, particularly those for ceilings next the roof of a house; as long joists are subject to warp, which breaks the plastering.

The distance from middle to middle should never exceed 12 inches, otherwise the bearing for the laths becomes too long. If the distance from middle to middle exceeds 12 inches, double laths should be used.

This Table is calculated by the rule .64l/b1/2 = d; where lis the length, d is the depth, and b the breadth.