Roofs and flat roofs
Are mortar-bedded ridge tiles a separate defect from the slates or tiles on the slope?
Yes. Ridges and hips are the units along the peak and the angles, often bedded in mortar. The mortar can crack and the units can lift while the slopes are still doing their job. A survey should rate what it saw, not fold the ridge into a vague “roof”.
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?
Failed ridge mortar lets wind-driven rain under the ridge and into the top of the roof. From the loft that can show as staining near the ridge boards. From the ground it shows as cracked, missing or open mortar and uneven ridge units. Re-bedding or a dry-ridge system is a different specification from re-covering the slopes.
Ask the surveyor whether the slopes, the ridge and the verges were each visible. A roofer’s quote should say which of those it includes. If the quote says “roof repairs” only, you cannot compare it with another. Scaffolding may be required for a ridge even when only a short length has failed. Ask the roofer. Do not guess a scaffold price.
What should you ask your surveyor?
- Were the ridges and hips inspected, or only the general slope?
- Is the mortar open, or are ridge units missing?
- Would you expect water in at the ridge even if the slates look even?
What are the typical next steps?
- Separate the ridge from the slopes when you ask for prices.
- Check the loft at the ridge if it was safe to enter. Staining there supports the outside comment.
- Do not replace a whole covering because the ridge mortar is tired, unless the slopes are also failing.
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
What is a dry-ridge system?
It is a mechanical fixing for ridge units that does not rely on mortar. Whether it suits this roof is a roofer’s specification, not a conclusion from the survey alone.
Do verge mortar and ridge mortar fail together?
Not always. Verges are the sloping edges. Ask about each if the report mentions only one.