How To Fix Sagging Roof Trusses. More than one roof coating may have been installed. This is a follow up from a previous question.

To fix a sagging garage roof you need to support or replace the beams. Tips for How to Fix Sagging Roof. Next place your piece of plywood and Styrofoam foam-side-up against the damaged roof decking.
The roof sags where the trusses if you.
Next place your piece of plywood and Styrofoam foam-side-up against the damaged roof decking. When the original roof wore out a second and maybe even a third roof was laid over the original roof. Place the truss patch over the sagging truss so that it is centered over the previously sagging area. There is a clear deliniation where the support wals end and begin again.

