Can a dry ridge go on a slate roof?

In place of wet mortar, a dry ridge uses a batten screwed along the apex with the ridge units clipped and screwed onto it. A flexible or rigid roll along each side closes the gap between slates and units, and ventilation can be built into it. Our guide to dry ridge systems explains the parts in full.

On a tiled roof the units overlap tiles with a profile to match. Slate is flat and thin, so the closure has to cope with a smooth, narrow edge. Kits designed for slate use an angled ridge unit with an adjustable closure, and some are tested for slate as well as tile. Check the manufacturer's data sheet to see which coverings a system is approved for. A kit tested to BS 8612 has met the recognised test for these systems.

The two slates behave differently under a dry ridge.

Natural slate

Natural slate is thin and hard, and the edges of old pieces are often uneven, which a closure strip has to tolerate. MyBuilder's 2026 guide gives it a typical life of 80 to 100 years or more, so the ridge you fit may be replaced long before the slates are. A dry ridge works well on a regular natural slate roof with a sound ridge board. It is less happy on a hand-dressed or irregular slate roof where the gap under the closure varies from tile to tile.

Fibre-cement slate

Fibre-cement or synthetic slate has a quoted life of 30 to 50 years from the same MyBuilder guide. It is uniform and light, which suits a dry ridge: the slates are even, so the closure fits neatly. If your roof carries older fibre-cement slate that may contain asbestos, tell us before any work starts, because careful handling and sometimes notification apply under HSE guidance.

Many old Stroud valley roofs are slate or stone slate with clay ridge tiles bedded in mortar, and some of those are better left that way. Mortar is flexible in the right mix and moves with an old roof, and a traditional clay angled ridge looks right with natural slate. If the house is listed or sits inside one of Stroud's conservation areas, changing what the ridge looks like may need consent, and the council can tell you whether it does.

Mortar also copes with irregular ridge lines, where a dry batten wants a straight, even line. If the ridge sags or the rafters are out of true, a bed can take up the difference, though it still needs mechanical fixing alongside. Even then BS 5534:2014 expects a mechanical fixing beside the bed. For a feel for the timing on older houses, how long a ridge repair takes can also help you weigh the options.

Lead is the other traditional answer on slate. A lead roll over a timber core, dressed down either side, gives a slim ridge line that suits fine slate and some stone-slate roofs. It lasts well: MyJobQuote's guide, updated in September 2026, puts lead flashing life at more than 80 years when installed correctly. It costs more than a tile ridge and it is a specialist trade, so it makes sense where appearance or durability matters, such as on a prominent slate roof or a church.

Where lead is chosen, the code matters. For ordinary flashings Code 4 is the usual weight, with heavier sheet kept for bigger details. A lead ridge has no ventilated closure built in, so a cold roof needs its own ventilation detail. We specify this on the quote rather than leave it to the day.

The choice between dry ridge, mortar and lead rests on the roof, not on fashion. One roof can even carry a dry hip and a lead ridge, provided the junction where they meet is designed properly and not left to chance.

Ventilation is a good reason to choose dry ridge. Many kits include an air path at the apex, helping a cold roof to breathe in line with BS 5250. That helps if your loft has condensation, though the eaves also need an air path. A roofer should check both before agreeing the ridge.

MyBuilder's 2026 dry ridge guide shows £40 to £60 per metre, and £500 to £1,000 for a typical job. Checkatrade's repair guide gives dry ridge at £50 to £70 per metre excluding VAT. Both are national ranges for tiled work, and a slate ridge can cost more where cutting and special closures are needed. Scaffold adds to every one of them.

A survey is the next step. We photograph your slates and ridge, look at the timber beneath, and the written quote then covers the ridge, closure, scaffold and labour. Slates that are cracked, delaminating or nail-sick are best dealt with at the same visit, since a new ridge on a failing slope only moves the problem along. The slate type, its age and the exposure all feed into the advice. Our work is backed by a 10-year workmanship guarantee in writing. Phone 01453 933613 or WhatsApp your photographs. Two related answers help: whether a leak can come through the ridge and the main page on ridge, verge and dry-fix repairs.