Hi. I have a 1 1/2 story Cape Cod style house. In 1984 I built a shed dormer across the back. The wall-ceiling joint in one room has kept breaking apart. At first I just retaped it and repaired it. It would only last till the weather would change. In the winter time everything contracts and the gap would gone. However in the summer time the roof, wall everything expands and the gap will reach at least an 1 1/2".
The side walls are built in from the roof edge abvout 8"- 12". The wall is built from the floor to under roof rafter. The drywall is attached to the ceiling joist untill it gets about 3 feet from the back wall. There it is attached directly to the rafter. Due to roof pitch restaints we had to lower the back wall. The worst part is where the where the drywall is attached to the ceiling joist. The angle part (last 3') is cracked but dosen't expand that much. The ceiling in the center, right under the peak (about 18" - 24" between ceiling and ridge) is fine. It's really hard to paint a picture of this but I am trying. I hope it's clearer than mud.
I have seen the cause of this adressed years ago in a newspaper colum. Gary Sullivan I believe. Of course I forgot. I need help figuring the cause and a solution. I remember the a proper repair was quite involved. Please help me solve this problem