Roofs and flat roofs
A dry-ridge system is on one slope and the other slope is still bedded in mortar. What age of the covering has the new ridge not reset?
The new ridge has not reset the age of the covering. A dry-ridge system on one slope is a modern fixing at the apex of that slope only. The other slope is still bedded in mortar, which is the older way of holding the ridge. The tiles or slates on both slopes keep whatever age and fixing they already had. The survey has recorded the split detail. It has not dated the covering, and it has not said the mortared slope was relaid when the dry ridge went on. One new ridge does not make the roof new.
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?
Dry-ridge systems fix the ridge tiles mechanically, with vents or gaskets, instead of a mortar bed. They can be fitted to an existing slope without stripping it. Seeing one on only one slope fits a partial job: that apex was redone, the other was not. Mortar on the second slope can be tired while the first looks fresh. Neither look dates the nails, the battens or the tiles below. The survey saw the two methods. It did not lift the covering to age it.
Tell the solicitor one slope has a dry ridge and the other is still mortared, so any claim that the roof was renewed needs paperwork, not the ridge alone. A roofer, if you instruct one, should comment on the mortared slope as it is, without assuming it shares the new ridge's age. The survey has not reset that age and has not specified a reroof. A guarantee for a dry-ridge kit, if one exists, would cover that kit, not the whole covering.
What should you ask your surveyor?
- Which slope has the dry ridge, and which is still mortared?
- Has the new ridge left the age of the covering unset?
- Was the covering left unlifted?
What are the typical next steps?
- Do not treat one dry ridge as a new roof.
- Note that the other slope is still bedded in mortar.
- Ask for paperwork if someone claims the covering was renewed.
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
If the dry ridge is ventilated, is the whole roof now vented?
Not by this note. Ventilation in a dry-ridge system is at the ridge of the slope it was fitted to. The other slope is still bedded in mortar, and the survey has not said that slope, or the loft, is ventilated. The new ridge has not reset the age of the covering either. One vented apex is not a whole-roof system.
Does mortar on the second slope mean that slope is about to fail?
The survey has not said that. Mortar bedding is the older detail still in place. It can be cracked or sound, and this note is the contrast with the dry ridge, not a failure date. The new ridge has not reset the age of either covering. Ask what the mortar looked like. Do not date a failure from the method alone.