The short answer
A ridge leaks when the bedding beneath its tiles has cracked or fallen out, when a ridge tile has slipped or broken, or when wind pushes rain up and under a dry system that is poorly fitted. The fix depends on the cause: repointing for sound tiles with failed joints, re-bedding for loose ones, and replacement of cracked tiles, with a mechanical fixing alongside in each case.
How a ridge lets water in
The ridge is built to shed water down both slopes, and the tiles that cap it are curved so rain runs off their sides. Beneath them sits the bedding, the mortar or the dry-fix strip that closes the space between the top row of roof tiles and the cap above. When that seal fails, rain has a route in at the very summit.
Usually the water does not pour. It trickles onto the underlay and battens at the top of the rafters, dampens the timber and then finds its way down a rafter or along a joint before dripping from the ceiling lower down. That is why the stain is rarely right under the fault, and why a leak that seems to belong to a bedroom wall can start at the peak of the roof.
A ridge is also the part of the roof most directly in the path of wind. A gale can drive rain sideways and upwards beneath the cap, through a gap that stays dry in ordinary weather.
The common faults, one at a time
Cracked and missing bedding comes first. Mortar shrinks, splits along its edges and drops out in pieces, leaving a dark gap and, over time, a loose ridge tile. The pointing at the ends of a run, where two slopes meet at a hip or a gable, usually fails first.
Next are the ridge tiles themselves. A tile can crack along its length, break at the joint or slide a few centimetres out of line. Because each tile overlaps its neighbour, one fault can open a path for water along the whole row.
Then there are the fixings. Some ridges rely on mortar with no screw, clip or strap behind it, and they may sit still until a hard winter and then shift. On a dry ridge, a missing or badly fitted vented roll or end cap lets in rain and leaves. A tile that has fallen off altogether is the most obvious case, and it is rarely the whole story, because the bedding next to it is nearly always compromised too. How long the work takes is covered on our page about ridge repair time.
Telling a ridge leak from other leaks
Damp near the top of the house might equally be condensation, a worn flashing or a tile that has dropped lower down. A few clues help separate them.
- Timing. A ridge leak appears after wind-driven rain, not after every shower.
- Position. Stained timber and wet insulation near the peak, rather than at the eaves or a chimney, point upward.
- Loft light. Daylight at the ridge from inside the loft shows a gap that water can also use.
- Visible faults. Fallen mortar in the gutter, a tilted tile or a crack seen from the garden confirm it.
Condensation looks similar but is damp across the whole underside, often with mould, and it comes with cold weather rather than storms. Your roofer can tell the two apart, and sometimes a simple measure such as ventilation solves the second. If the ridge is the source, the survey identifies exactly which section has failed.
Repairs that actually stop it
When the tiles are firm and just the joints have broken down, repointing is often enough: loose mortar is raked out and new mix is packed in, with a mechanical fixing added. Our page on dry ridge cost gives a sense of what the other route costs.
Where tiles are loose, cracked or out of line, the run is lifted, the old bed is cleaned off and the tiles are laid again on fresh bedding and fixed down. Broken tiles are replaced with matching ones. If the whole ridge is old and the bedding is shot from end to end, a dry ridge system is an option: units are screwed or clipped to the battens, with a ventilated roll below, and no mortar is needed.
Which route is right depends on the age and weight of the tiles, the pitch and the look of the roof. As a rough marker, MyBuilder's dry ridge price guide (updated August 2026) gives about £40 to £60 per linear metre for a dry ridge. That is a national range, not a quote for your house.
Sealant or a strip of tape rarely lasts, and it can disguise the fault from whoever inspects the roof next. A leak is dealt with by making things safe first, and then by choosing the least work that cures the actual cause.
Access, edges and what to do now
Reaching the crest safely is a job in itself. On a two-storey house it usually calls for scaffolding or a tower, and our page on scaffolding for ridge work explains when that is needed and why it can outweigh the repair. Keep your feet on the ground and let the camera do the looking.
The verge, the edge where a slope ends at a gable wall, can leak for the same reasons, and a failing verge undercloak sometimes shows up as damp near the same corner of the loft. For the whole group of repairs, start at ridge and verge dry-fix.
Meanwhile, put a bucket or a towel under any drip, move belongings away from the stain, and photograph it with the date. If you can see the ridge from the ground, photograph that too. A survey brings back photographs of the ridge as it is, and the quote arrives on paper. Repairs are guaranteed for workmanship over a ten year period, in writing, and removed material leaves with us.