Damp and moisture meters

If the underside of the roofing felt is wet on a cold morning, is that usually a leak?

Not necessarily. Water on the underside of the felt on a cold morning can be condensation in a cold roof. The Building Research Establishment reports that drips in a cold roof are often condensation, not a leak. A home survey can record wet felt, but it does not prove a hole from one cold morning.

Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.

What is the fuller explanation?

Cold roofs pick up water vapour from the rooms below. On a cold morning that vapour can sit on the underside of the felt as beads, and those beads can drip onto the quilt or the ceiling. The Building Research Establishment reports that drips in a cold roof are often condensation, not a leak. The clues are wet felt with the tiles still lying properly, and moisture that does not line up with a gap you can see daylight through. A surveyor in the loft can record the beads. They cannot see every tile fixing from below.

A RICS home survey is visual. It does not run a condensation calculation and it does not guarantee the covering. One cold morning is not a whole winter. If the felt is wet and no tile is out of place, do not start with a new roof. Ask whether the eaves were blocked, whether a fan or a cooker duct ends in the loft, and whether any stain indoors lines up with a real gap. A true hole still exists in some roofs. The point is not to assume the covering has failed because the underside was damp at dawn.

What should you ask your surveyor?

Was the felt wet while the tiles you could see were still in place?
Did any drip line up with daylight through the covering?
Were the eaves open, or was the loft closed up?

What are the typical next steps?

Do not replace the covering because the underside of the felt was wet on a cold morning.
Record blocked eaves, ducts into the loft, and any real gap as separate items.
If you need a cause, ask for a roof inspection that will say condensation, a covering defect, or both.

Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.

Also asked about this

Does wet felt on a warm afternoon mean the same thing?

Not always. Afternoon wetting after rain is more suspicious of a leak. The cold-morning pattern is the condensation clue.

Will more quilt alone stop beads on the felt?

Not if the vapour still enters a closed cold roof. Stuffing the eaves can make the void wetter.