We have a crack in the ceiling drywall. Last summer, the house must have settled due to a drought. The crack runs along a rafter the full width of the living room. I am debating whether to lay a piece of plywood with 2 x 4 blocks screwed to it between rafters and run screws through the drywall and into the plywood. Once I have the drywall screwed to the plywood, I will go back and screw the blocks to the rafters. I have a spackled ceiling, I will remove enough spackel for a joint seam and paint. The other solution I see is to remove the drywall between the rafter and replace it. I don't like the idea of fighting insulation falling in the living room, but I removed most of it between the ratters already.