I have a sagging gambrel roof. After pulling and reinforcing the structure much of the sag still remains.
I want to know the proper way to shim 2x4 purlins and put a metal roof on. The question is how much sag can be or should be shimmed to get the metal straight? Can furring strips or even 2x4 be used vertical (parallel) over the top edge of a rafter to shim out the purlins? Can deck screws be used to attach the shim to the rafter and the purlin to the shim?