I recently had a ceiling removed as part of asbestos abatement. The ceiling joists are 24" apart. They run about 20' long and the area is about 8 1/2' wide. What's the best way to avoid the ceiling drywall from sagging and creating a rippled effect?
Would 5/8" drywall be sufficient? If so, should I get 4x10 and run the long side perpendicular to the joists? If I do that, I may not be able to get the ceiling drywall above the in-place wall drywall (you know, the 1/2" or so the wall's drywall sticks out). Or should I do 4x8 with the long side following the joists? That makes it feasible to slide the ceiling pieces above the existing wall drywall.
Or, should I add more joists between each pair of joists? There is a beam about in the middle (which I'm going to raise into the attic and attach the joists to it with joist hangers), so these new joists would only be 10-12' long each. If I do that, would 1/2" 4x8 drywall be sufficient?