Dry ridge on old roofs
Can dry ridge be fitted to an old roof?
The short answer
Often yes. A dry ridge can be fitted to many older roofs, provided the tiles are a profile the kit is made for and the timbers at the top of the roof are sound. It suits some traditional or reclaimed coverings less well, and BS 5534 itself says its recommendations might not fit every old roof. A survey of the ridge decides it.
What an older roof has to offer a dry ridge system, where problems come from, and how listed and conservation area homes are treated.
What the old roof has to offer a dry ridge
In place of a mortar bed, a dry ridge carries a fixed rail or batten; clips or screws hold the capping to it, and factory-made seals close the gaps. It only works if the rail has something solid to fix back to. On an old roof that means a sound ridge board or rafter ends, a straight line of top battens and enough of the top courses of tiles to take the fittings.
The system also has to sit on the right tile. Dry kits are tested against BS 8612:2018, the British Standard BSI lists as current for kits of that kind. A maker's data sheet lists the tiles each kit is made for, and an old roof tile that is not on the list is a reason to ask more questions.
None of this rules out an older house. It simply means the roof is looked at first. Our guide to dry ridge systems shows what the parts are and how they go together.
When the tiles are the problem
The trouble with some old roofs lies in the covering, not the timber. Hand-made clay tiles, reclaimed pieces and unusually shaped plain tiles do not sit to the tight tolerances a manufactured kit expects. BSI itself warns that BS 5534 may not suit every older roof, above all one built with traditional or reclaimed materials.
On a roof like that, a dry system can leave gaps at the seals or a rail that sits unevenly, and a bedded ridge with a fixing driven through each tile may be the better answer. Neither route is wrong. What matters is that the ridge is held to the structure by something more than adhesion, and that the finish keeps the weather out.
If the roof is a standard concrete or machine-made clay tile from the last few decades, a dry system is usually straightforward to fit. A survey tells us which case applies to your house.
What we check at the top of the roof
Taking the old ridge off reveals the peak of the roof, which nobody normally sees. We look at the ridge board, the uppermost batten, the underlay where the slopes meet and the rafter ends. If the timber is soft, split or wet, the rail has nothing to bite into, so the timber has to be repaired first.
The old bed is cleared as well. A dry ridge is not fixed over the mortar, because a rail needs a clean, true seat, and loose old bed under the new capping would only break away. Any sound capping tiles can be set aside and reused if they match the new fittings, while cracked ones are replaced.
Anything we uncover is photographed and explained to you before the written quote, which remains one total price, is adjusted. Our guide to repointing against dry ridge goes through the decision for the common cases.
Period homes, listed buildings and the look from the street
On a period house the bedded line of mortar belongs to the look. Dry fittings are colour matched and can look tidy, but they do not look the same as a bedded ridge, and a conservation area home may want the traditional appearance kept. Arun's guidance for the seafront conservation areas asks owners to reinstate original materials rather than replace them with modern ones.
A listed building needs listed building consent for work that changes its character, while plain maintenance is treated more lightly. Planning permission is not usually required to re-roof in matching materials, but listing and Article 4 directions can alter that, so check with Arun District Council's planning team, or the council for your own area, first.
Our page on ridge tiles and Building Regulations explains where approval comes into a ridge job.
Dry or bedded: which suits an old roof
Both routes are accepted in practice, and neither is a second-best choice. Bedding the ridge and fixing each tile mechanically suits a roof where the look of mortar matters and the tiles do not suit a kit. A dry ridge suits a roof where the old bed has failed, the line has dipped or the owner would rather have no joints to maintain.
Marley's guidance is that installing to BS 5534 is not required by law, so you are making a choice about durability and appearance, not meeting a legal test. The choice is easier with photographs of the apex, the tiles and the existing ridge in front of you.
We give a plain verdict on which route fits, based on the condition of the roof as it is, and we recommend the smaller job where a repair will hold. The wider picture is on our ridge tile repairs page.
Related questions
Old roof dry ridge questions
Will a dry ridge straighten a ridge that has dipped?
The new rail sets a fresh line for the capping, which can hide a mild wave in the old bed. A real dip in the roof itself is a different matter and may come from the timbers beneath. We check that at the survey, and an engineer's check may be worth having if the frame has moved, since no ridge system can correct a roof that has shifted underneath it.
Can the new rail be fixed over the old mortar?
No. The old bed is chipped away so the rail sits on a clean, true seat and the courses below can be inspected. Fitting over loose mortar would leave a weak seat that breaks up and lets the fittings move. Clearing it is part of the job.