The short answer
A visibly sagging or wavy roof line means something beneath the shingles has lost strength: decking, rafters or the ridge. It is structural rather than cosmetic. A slight wave on an old roof is common, but a defined dip, a sagging ridge, or any sag that is getting worse should be inspected promptly.
What causes it
| Cause | How you can tell | How common |
|---|---|---|
| Rotted or delaminated decking | Localized dips between rafters, soft underfoot | Common |
| Long-term water damage | Sag near a chronic leak point | Common |
| Undersized framing or overspan | Even sag along a long run | Needs an engineer |
| Too many roof layers | General sag on a double or triple-layered roof | Weight problem |
| Failed ridge beam | The peak itself dips | Serious |
| Foundation movement | Sag with doors sticking and wall cracks | Not a roof problem |
How fast do you need to act
Have it looked at within days. A sagging ridge or a sag that has visibly changed is a reason to get a structural opinion quickly rather than a roofing quote.
What to do right now
- Photograph the roof line from across the street, straight on
- Compare against an older photo of the house if you have one
- Check inside the attic for cracked rafters, separated joints or daylight
- Note whether doors and windows have started sticking, which points at the foundation instead
- Get a structural engineer rather than only a roofer if the ridge itself is dipping
What we see in the Hill Country
Foundation movement in Hill Country clay soils can read as a roof problem from the street. Before paying for roof structural work, it is worth ruling out that the house itself has moved, because the fix and the trade involved are completely different.
When to call us
We inspect for this at no charge across Boerne, San Antonio, New Braunfels, Kerrville, Fair Oaks Ranch, Bulverde, Helotes, Spring Branch, Austin and Stone Oak. You get photographs of what we find and a written explanation, including when the honest answer is that nothing needs doing yet. Call (210) 245-4125 or book an inspection.
