Ceiling

A Southern Pine garage ceiling with 2×6 joists spaced 16 in. on center has a 4,000 lb. per sq. ft. (psf) weight load capacity. If that garage ceiling will potentially support snow, then the hanging weight for this garage ceiling drops to 2,000 lb.

If those joists are spaced 24 in. on center rather than 16, the clear roof supports 3,500 lb. psf, and the snow roof supports 1,500 lb. psf.