What ridge goes on a slate roof?

1The three usual choices

At the apex of a roof, where two slopes meet, the slates stop just short and a separate cap closes the gap, because slates cannot be bent over the top themselves. Three kinds of cap are common on slate roofs.

Clay ridge tiles are the traditional choice. They are made half-round, angled or with a decorative crest, and many Victorian terraces near the seafront carry them. Concrete ridge tiles do the same job in a plainer finish and are widely used on later repairs. Dry-fix systems are a more modern method: the tiles are held by a ridge batten, clips and fixings, with a flexible roll or sealing strip along the edges in place of most of the mortar.

Which is right depends on the building. A period roof usually keeps clay, a plain 1930s roof can take concrete, and a roof that has lost its mortar repeatedly often does better on dry-fix.

2Why mortar alone is no longer trusted

Mortar bedding used to be accepted on its own. Marley explains that once BS 5534 was revised, mortar by itself was no longer trusted to carry ridge and hip tiles, so a bedded fitting also receives its own mechanical fixing. A hip is the sloping edge where two roof faces meet. Mortar is still used to bed the tiles; it is simply not the only thing holding them.

Marley is also clear that installing to BS 5534 is not required by law. It is the code of practice, and a roofer who follows it fixes a ridge so that it survives wind suction. That matters on a south-coast roof, where storms can pull at a ridge for hours. A ridge tile held only by cracked mortar is one gale from sliding off.

Mortar is not banned. A well-bedded ridge with proper mechanical fixings is sound, and on a period roof it is frequently the better fit.

3Dry-fix ridges on slate

BS 8612:2018 is the standard that tests dry-fix kits for ridges, hips and verges, and Marley points to it for kits of this type. A dry ridge does away with most of the wet mortar, so there is little to crack, shrink or wash out.

On a slate roof, the system sits on the apex with the tiles held down on the ridge batten by the fixings. The edges are closed against the slates by the roll or strip, so the slates stay visible and the ridge reads as a clean line. It suits roofs where the old mortar has failed more than once.

Costs, as published: MyBuilder's guide of 21 August 2026 gives £40 to £60 for each linear metre of dry ridge, and £500 to £1,000 for a typical job. Checkatrade gives £50 to £70 a metre. For comparison, MyBuilder puts £300 to £600 on re-bedding or replacing the ridge. These are typical UK ranges, and your roof is priced after a survey.

4Old roofs, conservation areas and listed buildings

Heritage roofs raise a different question. Marley notes that the 2018 amendment admits that the standard may not suit a historic roof, and recommends consulting the council and conservation advisers. A listed building's ridge is part of its character, and swapping a clay crest for a plain concrete one is the sort of change the council will want to see first.

In some conservation areas the rules reach further. In Old Shoreham and Kingston Buci, Article 4 directions remove the usual permission to change a roof covering on a street-facing house, and to alter a chimney. Check with the Adur & Worthing planning team before changing a ridge on a road-facing roof there.

Period detail is worth keeping. Victorian ridges often have decorative crests that can be refixed when the roof is relaid. Our guide to Victorian slate roofs covers what to look for.

5Signs the ridge is failing and what we do

From the ground, look for tiles that sit crooked, gaps along the ridge line, bits of old bedding mortar lying in the gutter, or a tile lying on the lawn. From the loft, watch for a stain or daylight at the top of the roof. Never climb on a slate roof to check; slates crack underfoot.

Repairs run from rebedding a few tiles to a full ridge replacement. We lift the old tiles, clear the mortar, check the timber beneath, then rebed with mechanical fixings or fit a dry-fix kit. A failing ridge is one of the causes in why slate roofs leak. If the slates below are also failing, repair or re-slate helps you decide. Where man-made slates are involved, see fibre cement slate lifespan. More slate topics are gathered under slate roofing, and a survey of the ridge line comes before any price.