Roofs and flat roofs
What can a survey say about the covering on a bay roof, separately from the main roof?
It can treat the bay as its own small roof, because many bays carry lead, felt or fibreglass that is not the main slope. The survey should say whether that covering was seen and what the rolls, drips or upstands looked like if they were in view, since a bay roof can be tired while the main tiles look even. Not seeing the top from the ground is a limit, not a pass, and the comment is about the covering itself.
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?
Bay tops are small, often hidden by the bay’s own cornice, and easy to leave out of a roof paragraph that only describes the main tiles. Lead bays fail at rolls and drips. Felt and fibreglass bays fail at outlets and at the junction with the wall. Those are covering defects. A home survey from the pavement may see only the fascia of the bay. It should say so, rather than implying the bay roof was inspected because the main roof was.
Ask a roofer to price the bay covering as its own item, with access, which may be a tower or a careful ladder, not a full scaffold for the house. There is no standard price. Do not paste the main-roof specification onto the bay. If the survey could not see the top, a “satisfactory” on the main slope does not borrow across. The wall under the bay is a different sentence and is not what this question is deciding.
What should you ask your surveyor?
- Did you see the bay covering, or only the bay from below?
- What is it made of, if you could tell?
- Is the main roof written up separately?
What are the typical next steps?
- Include the bay top in any roofer’s visit, even if the main roof looks fair.
- Do not assume a recent main-roof invoice includes the bay.
- If the top was not seen, say that when you compare quotes.
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
Is a tiled bay roof the same question?
It is still a separate covering from the main roof. The details are tiles and hips rather than a flat sheet. Ask which you have.
Does a leak at the bay mean the main ridge has failed?
No. Water follows the bay. Do not rebuild the main roof for a bay defect unless that defect was actually seen there.