When installing sheet rock on walls or ceilings, be sure to stagger the seams at the butt joints. If the butt joints are all on the same stud or joist, they will eventually crack. For example, when hanging 8' rock on a 12 foot wall, hang the first piece at the top left. Then hang the 4' piece at the top right. Then start the bottom left with a 4' piece so that the seams don't line up. Then hang the last 8' piece at the bottom right.