Bumps and cracks every two feet where the ceiling meets the wall: truss uplift, screw pops or a problem?

A bump that repeats at the same interval sits where the drywall is screwed or nailed to framing. The Gypsum Association's repair guide, GA-222, lists the causes of such fastener pops: lumber shrinking after the board is hung, loose attachment, twisted or bowed framing, fasteners that are too long, poor fastening and shrinking drywall adhesive. Shrinkage of lumber that went in wet is the main one. Pops that show up a month or more into the heating season usually come from it and should wait until the season ends. The guide's repair is a new fastener about 1-1/2 inches from the pop, with the panel pressed tight to the framing, and the old head reset just below the surface or pulled.

A crack along the ceiling-wall joint is often truss uplift. Kelly Sias, an engineer at connector maker Simpson Strong-Tie, describes it as a gap between interior walls and the ceiling that opens in winter and closes in summer. One cause she lists is attic moisture: the top and bottom chords of a truss take on and lose moisture at different rates through the seasons, so the truss arches and lifts the ceiling off the wall. Sias writes that arching from normal wood shrinkage and swelling does not signal a structural problem.

The cure is to let the ceiling float. Simpson's detail uses slotted clips between truss and wall, drywall clips at the corner, and no ceiling fasteners into the bottom chord within 16 inches of the wall.

Sias also lists causes that are not cosmetic, such as foundation settlement and expansive soils. Gaps that keep widening through the summer, instead of closing, point there, and new tape and paint will not hold.