Seasonal movement of roof trusses can cause gaps to open up at the wall/ceiling intersection. Lower truss chords that touch a warm ceiling will dry out and shrink during the heating season, while colder upper chords gain moisture and expand. The moving truss can create cracks where walls and ceilings meet.
1. For Parallel Walls
When trusses run parallel to partitions, install 2x6 nailers for fastening the ceiling drywall to prevent drywall cracking due to truss uplift. Do not fasten the drywall to the bottom chords near partition walls.
2. For Perpendicular Walls
When trusses are perpendicular to the partitions, install blocking to attach the ceiling drywall, and hold fasteners back 12 inches to 16 inches on either side of the partitions.
3. For Existing Homes
The gap can be hidden with a strategically fastened cornice molding. Triangular blocks nailed into the ceiling only provide a nailing base for this crown molding, which can move relative to the flat trim on the wall.