Flat Roof Blistering
Raised bubbles or blisters appearing on the surface of a flat roof, sometimes soft to touch.
What Is Causing This?
- 1Moisture trapped beneath the felt during installation
- 2Prolonged sun exposure breaking down the membrane
- 3Poor adhesion between layers of the roofing material
How Urgent Is This?
This should be fixed in the coming weeks. Leaving it may allow the problem to worsen and cost more to repair.
What Needs to Be Done
A roofer will cut open the blister, dry out the moisture beneath, and patch or re-cover the affected area. For widespread blistering, the entire roof membrane may need replacing.
How Much Will It Cost?
National average estimate
Labour: £975 – £2,575 | Materials: £725 – £2,050
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Prices are estimates based on typical UK rates. Actual costs depend on the specific issue, accessibility, and your location. All quotes from tradespeople on Tradesfolk are completely free.
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Some fixes for this problem may require planning permission or building regulations approval. Check if your project needs permission:
How to Prevent This
Have flat roofs inspected annually. Apply a reflective coating to reduce heat damage. Ensure drainage falls prevent standing water.
Related Problems
Other Roofer Problems
One or more roof tiles have slipped, cracked, or blown off, leaving exposed areas on the roof.
Water coming through the roof into the loft space or directly through the ceiling, often during or after rainfall.
The ridge line along the top of the roof has a visible dip or sag instead of running straight.
Rainwater overflows from the guttering during rainfall, running down the outside walls of the house.