A roofing pro may find that the roof is sagging due to rotten sheathing. If water has penetrated through shingles, the plywood can warp, weaken, or rot, so that the roof looks as if it’s sagging between rafters. Or they could identify a framing issue as the cause of the sagging. If your roof is showing signs of sagging, don’t wait to hire a pro to investigate the problem. A pro will have the experience, tools, and knowledge to repair your roof safely and efficiently.