Condensation in Loft
Visible moisture, water droplets, or damp patches on the underside of the roof felt or rafters in the loft space.
What Is Causing This?
- 1Inadequate loft ventilation blocking airflow
- 2Warm moist air from the house rising into an unventilated loft
- 3Bathroom or kitchen extractor fan venting into the loft instead of outside
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 improve ventilation by adding soffit vents, ridge vents, or tile vents. They will also check that extractor fans vent to outside and that the loft hatch is draught-sealed.
How Much Will It Cost?
National average estimate
Labour: £975 – £2,575 | Materials: £725 – £2,050
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Ask a QuestionPlanning Permission Guidance
Some fixes for this problem may require planning permission or building regulations approval. Check if your project needs permission:
How to Prevent This
Ensure extractor fans vent to the outside, not into the loft. Keep the loft hatch sealed. Do not block soffit ventilation with insulation.
Related Problems
Water coming through the roof into the loft space or directly through the ceiling, often during or after rainfall.
Black or dark green spots spreading across the bathroom ceiling, sometimes extending down the walls.
Moisture forming on windows, walls, or the inside of the roof slope in a loft conversion.
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.