Roof Problems · For owners & managers
Blisters on Flat Roofs: When to Leave Them and When to Fix
Blisters are bubbles between roof layers, caused by trapped air or moisture that expands in heat.
Low-risk blisters
Small, intact blisters may only need monitoring.
Higher-risk blisters
Cracked or large blisters, or ones in walk paths, can let water in and should be repaired.
Repair
Repair usually means cutting out the blister, drying the area, and patching with compatible material.
Common questions
- Do blisters mean wet insulation?
- Not always, but they can. A moisture check helps.
- Do they grow in summer?
- Heat expands trapped air, so they can.