Thanks,Canuk...I have heard of truss uplift..Will this worsten with time ? Also,is this difficult to fix ? Ihave been told it was easier to fix cosmetically but would rather have it done right.
I personally encountered this issue when purchased a new house 18 years ago.
The problem showed the first winter ... and figured the framing needed to acclimate ... so the when warmer temps arrived and the gap closed the repairs to the drywall joint was painstakingly made with tape and compound. The next winter the issue reappeared which meant this was going to be an ongoing issue.
The issue is the drywall for the ceiling is attached to the bottom of the trusses. When these trusses "lift" they move the ceiling drywall up and causes the separation between the wall and the ceiling.
The cure to this issue would require isolated framing installed in the attic space to fasten the ceiling drywall . The existing fasteners that secure the drywall would have to be cut from the bottom of the trusses .... this would allow the trusses to move and not bring the ceiling drywall with them.
In my case the cosmetic approach was done.
Molding was fastened to the ceiling only and not to the wall .... this molding would extend down the wall far enough to cover the gap during it's widest point .... when the ceiling moved upward during the winter ..... the molding would move with the ceiling not exposing the gap.
Hope this helps.:)