Condensation or Roof Leak? How to Tell the Difference, by Problem Homes UK on YouTube. 2 min 16 s.
- Video length
- 2 min 16 s
- Time to do it
- 20 minutes
- Difficulty
- Easy
- Steps
- 9
What you need
Steps
Check when the damp appears. Condensation often shows in cold weather even when it has not rained, while a roof leak is more likely to follow rainfall.
Look at how widespread the water is. Condensation tends to affect several surfaces, while a leak is often localised, though water can run along timbers before it drips.
Record the pattern for a few days. Note rain, temperature and where the damp returns so you can compare the clues.
Inspect the ceiling patch from below. Photograph it or mark its outline, then compare it after rain to see whether it grows.
Enter the loft with a torch and check roof timbers, felt, slates and tiles for runs, drips or damp patches.
Check the insulation. Damp insulation near the eaves or under felt points to condensation, while a wet patch under a damaged covering points more to a leak.
Look for blocked ventilation. Clear obstructions at eaves vents and check the gaps around the loft hatch and light fittings.
Use a dehumidifier only as a moisture test. It may lower household moisture, but it cannot fix blocked roof ventilation or a defective roof.
Call a roofer if you find an active drip during rain, missing or broken slates or tiles, or water tracking along timbers.
Tips and common mistakes
Use a stable step ladder and ask someone to hold it; do not climb into a loft alone if the hatch or boards are unsafe.
Do not assume every ceiling stain is a leak, because condensation can collect on cold felt and timbers and then drip.
A dehumidifier can reduce moisture in the home but will not repair blocked roof ventilation or a damaged roof covering.
Photograph the damp patch before and after rain so you can see whether it changes.
Questions
Can condensation drip onto a ceiling?
Yes. Moisture can collect on cold roof felt or timbers in the loft and then drip onto the ceiling below.
Will a dehumidifier stop loft condensation?
It may reduce household moisture, but it cannot fix blocked roof ventilation or a defective roof.
When should I call a roofer?
Call a roofer if you find an active drip during rain, damaged slates or tiles, or water tracking along roof timbers.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
