Question

True or false (for lumber in the United States):

A. Joists are customarily specified in terms of nominal sizes, but calculations to determine the allowable span and required modulus of elasticity are based on actual size.

B. A "two-by-four" is typically half an inch less deep and a "two-by-eight" is typically three-quarters of an inch less deep than the nominal size (actual depths are 3.5 inches and 7.25 inches, respectively).

Answer

Both A and B are true.