Soft Spots on Roof: Causes, Danger and How They Are Repaired
Soft spots on roof? They usually mean rotted or wet decking. Learn why they form, why you should not walk on them, how to check from the attic.
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Soft spots on roof surfaces usually mean the plywood or boards beneath the shingles have absorbed water and started to rot. This is a structural problem as well as a leak problem, and walking on a soft spot can be dangerous. Do not go onto the roof to test it.
Check from the attic, document what you see, and call a roofer to assess and repair the deck.
Soft spots on roof: why they are serious
The roof deck, or sheathing, supports the shingles, the people who walk on them and the load of snow. When it gets wet repeatedly, it softens and loses strength. A soft spot may fail under weight, and hidden rot can spread.
| Quick facts: soft spots on roof | |
|---|---|
| What they are | Areas of rotted, wet or weakened roof deck |
| Danger | Collapse under weight; fall hazard |
| Check from | The attic first |
| Fix | Replace the damaged sheathing and fix the leak source |
Causes
- Long-term leaks from failed flashing, vents or shingles.
- Poor attic ventilation, which traps moisture and causes condensation.
- Ice dams that push meltwater under shingles.
- Clogged gutters that back water onto the edge.
- Rotted deck near chimneys, skylights and vents.
- Old age of the roofing and underlayment.
How to check safely
- Do not walk on the roof to look for soft spots; you can fall through.
- Go into the attic with a flashlight on a dry day. Look at the underside of the deck for dark stains, damp wood, mold, rusty nails, sagging or daylight.
- Press gently on suspect areas with a screwdriver from below. Wood that is soft or crumbles is rotted.
- Look at the ceiling below for stains or sagging drywall.
- From the ground, look for dips or waves in the roof line, with binoculars.
What the repair involves
A roofer removes the shingles and underlayment over the damaged area, cuts out the rotted sheathing, replaces it with new plywood or boards fastened to the rafters, and installs new underlayment and shingles. The cause of the moisture, such as a leak or poor ventilation, must also be fixed. If rafters are damaged, a carpenter or structural repair is needed.
When soft spots mean replacement
If soft areas are widespread, the roof is old, or the sheathing is affected across slopes, replacing the whole roof is more sensible than patching. A roofer can inspect the deck at tear-off and replace boards as needed. Soft spots on roof decks are often found when old shingles come off.
Planning the repair
A roofer will usually measure the damaged area, check how far the rot extends along the rafters, and note whether the insulation below is wet. Repairs are easier in dry weather, and the roof should not be left open overnight without a temporary cover. If the leak came from a vent, chimney or skylight, that flashing should be fixed in the same visit, otherwise the new deck can rot again. Ask for the deck work to be itemised, with the number of sheets being replaced, so you can compare quotes on equal terms.
Immediate precautions
Keep people and heavy loads off the roof. If the ceiling below is sagging or wet, place buckets and consider moving furniture. A tarp can reduce water entry while you wait for repair.
Insurance
Rot from long-term leaks is often excluded as maintenance, while sudden storm damage may be covered. Document everything with photos and check your policy.
Prevention
Maintain flashing and shingles, keep gutters clear, ventilate the attic, and fix small leaks promptly.
When to call a professional
Call a roofer if you find soft or spongy areas, sagging, or signs of water in the attic. Do not wait for the next storm.
Soft spots on roof: why they form
Soft spots on roof decking form when water has soaked into the wood for a long time and started to rot. Walk the roof only where it is safe, and press gently on the surface to feel for give. Soft spots on roof surfaces often sit near valleys, chimneys and vents where leaks collect. A roofer can confirm the extent by checking from the attic, since the wood may be worse than the shingles suggest. Finding soft spots on roof sections early keeps the repair small and affordable. Replacing the decking in the affected area is usually needed before new shingles go on.
Related reading
- How Much Does a Roof Inspection Cost? What Sets the Price
- When to Replace a Roof: 9 Signs and How to Decide
- Practical Guide: How to Find Where a Roof Is Leaking
- Roof Inspection After Storm: Safe Checks, Evidence and Next Steps
Browse all roofing guides, or find a roofer in your city from the roofing directory.
Frequently asked questions
What causes soft spots on a roof?
Long-term leaks, poor attic ventilation, ice dams, clogged gutters and rotted flashing areas let water soak the roof deck until it softens and rots. Age of the roofing and underlayment also contributes.
Is it safe to walk on a roof with soft spots?
No. A soft spot may give way and cause a fall. Check from the attic or from the ground instead, and let a roofer assess the roof with proper safety equipment.
How do I check for rotten roof decking from the attic?
On a dry day, use a flashlight to look at the underside of the roof deck for dark stains, damp or soft wood, mold, rusty nails, sagging and daylight. Press suspect areas gently with a screwdriver to see if they are soft.
How are soft spots on roof decks repaired?
A roofer removes the shingles and underlayment, cuts out the rotted sheathing, installs new boards fastened to the rafters, then replaces the underlayment and shingles. The cause of the moisture must be fixed too.
Does a soft spot mean my whole roof needs replacing?
Not necessarily. Isolated rot can be repaired, but if soft areas are widespread or the roof is old, replacement is often more sensible. A roofer can inspect the extent of damage.
Will insurance cover rotted roof decking?
Rot from long-term leaks is often excluded as maintenance, while sudden damage such as a storm may be covered. Policies differ, so photograph the damage and check with your insurer.
Can poor attic ventilation cause soft spots?
Yes. Warm, moist air that cannot escape condenses on the underside of the roof deck, keeping it damp and encouraging rot. Good ventilation and air sealing help prevent it. Check that insulation is not blocking the vents.
When should I call a roofer for soft spots on my roof?
Call as soon as you notice soft, spongy or sagging areas, or stains and dampness in the attic. Delay can lead to bigger structural damage and a higher cost to repair.
How are soft spots on the roof repaired?
A roofer removes the shingles, cuts out the rotted decking, replaces it with new sheathing and re-roofs the area. Fixing the leak that caused the rot is part of the repair.
Can I tell if the roof deck is rotting from the attic?
Look for dark stains, sagging, soft or crumbly wood and daylight. Press gently with a screwdriver to check, and call a roofer if the wood is soft. Photograph soft spots and mark them with chalk so that a roofer can find them quickly from above.
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