Can a Cracked Ridge Tile Be Repaired?

Why ridge tiles crack

Ridge tiles sit along the top of the roof where the two slopes meet. They are exposed to wind, rain, frost and sun from every side. A tile may crack because the mortar beneath has shrunk and left it unsupported, because the roof has moved slightly, because a tile was knocked by a ladder or a branch, or because frost has got into a small flaw and opened it.

Thermal movement is a quiet cause. The ridge heats and cools faster than the tiles below it, and a long run of rigidly bedded ridge tiles can crack at the joints. Age is another: concrete and clay both weaken over decades. If you want to understand why ridge tiles fail in general, our answer on why ridge tiles come loose covers the main reasons.

When a crack can be left or sealed

A very fine surface crack that does not run through the tile, on a ridge that is otherwise sound, can sometimes be monitored. Photograph it and check again after the winter. If it has not changed, a flexible sealant or a bituminous repair can buy time. That is a temporary measure, and it needs to be done in dry weather on a clean tile.

If the crack runs through the tile, if you can see light through it or if the two halves move, sealant is not a repair. Water will get in, freeze and widen the break. Tape and mastic hide a crack but do not restore the tile, and they trap water against the mortar.

How a cracked ridge tile is replaced

The roofer removes the damaged tile, cleans out the old mortar, and sets a new tile of the same profile on fresh mortar, with the joints pointed. Where the surrounding mortar has gone, a longer section may be re-bedded. For a single tile, it is a short job, but the new tile must match the profile and be fully supported, or it will crack again.

On a ridge that has several failing tiles or mortar, the better answer may be to take the whole ridge off and re-lay it, or to convert to a dry ridge system. Our page on re-pointing versus re-bedding ridge tiles sets out the difference.

Mortar or dry fix

BS 5534:2014 expects ridge, hip and verge components to be mechanically fixed, and not relied on to stay put with mortar alone. A dry ridge system holds the tiles with clips and a ventilated batten, so there is no mortar to crack. If the mortar bedding is tired along the whole ridge, a dry system may be the sensible answer. Our comparison of dry ridge versus mortar weighs them.

For one cracked tile on an otherwise sound mortar ridge, a like-for-like replacement with a mechanical fixing is fine.

What the ridge is doing for the roof

The ridge is more than a cap. It closes the top of the roof against rain, and it holds down the top row of tiles on both slopes. If the ridge is open or cracked, rain can run into the gap, and wind can get under the top course. On some roofs a ventilated ridge also lets damp air escape from the loft. So a crack here is a small fault in a position where the consequences are larger than they look.

Signs the cracked tile is part of a bigger problem

Look at the mortar either side of the crack. If it is crumbling, hollow-sounding or missing, the bedding has failed, and replacing one tile will not solve the problem for long. Look at the neighbouring tiles for shifts or gaps. Check the ridge end caps and the point where the ridge meets the hips. A loose run of ridge tiles or a ridge that wobbles needs more than a single repair, and our answer on what to do when a ridge tile has fallen off covers that situation.

Cost and what to expect

A single ridge tile is a small job, though access and scaffold are the main cost drivers. Our guide to ridge tile repair cost gives typical UK ranges, and the fixed quote comes after the survey. We photograph the crack and the bedding so you can see whether a single tile is enough. For the wider picture, see the ridge tile repairs page.