Roofs and flat roofs
What should you ask if a stain sits under a roof window but the tiles around it look tidy?
Ask about the flashing kit and the frame, not only the tiles. Roof windows leak at the junction: the flashing, the lining, and sometimes condensation on a cold frame. Straight tiles do not prove that junction. A survey from the loft can see a stain and still not see the outer flashing.
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?
The covering and the window are different elements. A slipped tile is one defect. A tired flashing around a window is another, and it can wet the plasterboard even when every tile is present. Condensation on the glass is a third thing, and it is not a hole. The surveyor should say which signs were there: drip marks, a wet lining, or only misted glass.
Replacing a roof window is not included in a sentence about the tiles. RICS surveys do not test the window or guarantee the flashing. If the rating matters before exchange, ask a roofer or the window manufacturer’s installer to look at that opening. There is no RICS price for a roof window. Take a quote for the window you have, not a forum average.
What should you ask your surveyor?
- Did you see the outer flashing, or only the lining from the room?
- Was the frame wet, the glass misted, or the boarding stained?
- Is the recommendation about this window, or about the covering as a whole?
What are the typical next steps?
- Do not reseal the glass and call it a flashing repair.
- Note whether the stain appears after rain or after a cold night.
- Get a quote for this window if you need a number. Do not spread that number across the whole roof.
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
Are old roof windows a fire risk the survey has tested?
A home survey does not fire-test a window. It may note condition and age if it can see them. Escape and glazing rules are a separate question if you are altering the loft.
Can you ignore a misted roof window?
Misting between panes means the seal has failed. That is a window defect. It is not, by itself, a leak into the roof structure.