Sagging or dipping roofline

Symptoms

• Visible dip or wave when looking down the roofline from the ground
• Sagging most noticeable between the ridge and eave
• Sometimes accompanied by interior cracks or doors sticking

Likely causes

• CommonWater-damaged or rotted rafters or deckingA long-term hidden leak can weaken the wood framing under a section of roof.
• PossibleUndersized or aging framingOlder homes sometimes have framing not built for modern roofing loads like multiple shingle layers.
• PossibleExcess weight from snow, multiple roofing layers, or added equipmentAccumulated weight can gradually deform weaker framing.
• Less commonFoundation or wall settling affecting the roof structureMovement lower in the house can sometimes show up as roofline distortion.

What to do

1. Look down the roofline from across the street in good light to confirm the sag isn't just a shadow or angle illusion.
2. Check the attic underneath the sagging area for water stains, rot, cracked rafters, or sagging sheathing.
3. Look for related interior signs like new cracks, sticking doors, or gaps at ceiling-wall joints.
4. Avoid piling snow, storage, or heavy equipment on or near the affected roof area.
5. Take photos of the sag from the same spot over a few months to see if it is worsening.
6. Get a structural inspection promptly rather than waiting, since a sagging roof can indicate an ongoing safety issue.
7. Follow the structural engineer's or contractor's repair plan rather than attempting to shore it up yourself.

Tools and parts

• Flashlight for attic inspection
• Camera

When to call a pro

Call a structural engineer or experienced roofing/framing contractor promptly to assess and repair a sagging roof.

Safety