The ridge is the capping on the apex, a row of curved or angled tiles covering the join between the slopes. Each tile rests on a mortar bed and, on a modern repair, is held down by a fixing as well. With age the mortar shrinks, splits and drops out, and the tiles start to rock. Re-bedding means lifting the ridge, clearing out the old bed and laying every tile again on fresh material.
This guide is about the method and its limits: what happens on the day, in what order, and why each step is there. Mortar recipes have their own answer, and so does the question of mortar against dry-fix. For the wider picture of work along the top and edges of a roof, see our ridge, verge and dry-fix page.
When lifting the whole ridge is the right repair
Not every defective ridge needs to come off. A single cracked joint on an otherwise firm run can sometimes be raked out and repointed. Re-bedding is the repair when the bed beneath the tiles has failed, not just the surface of the joints. The signs are fairly plain from the ground with binoculars and plain at close range: tiles that sit at slightly different heights, gaps where daylight shows under a tile, mortar that has dropped into the gutter, and joints that crumble when touched.
On the roof we test the ridge by hand. A firm tile does not move. A tile on a failed bed rocks or lifts, and when we lift it we can see whether the mortar underneath is still holding or has turned to sand. If the failure runs the whole length, re-bedding the lot is cheaper over time than patching it in sections, because the next section to go is usually the one beside the last repair.
What the national guides say it costs
MyBuilder (updated August 2026) gives £300 to £600 as the typical range for lifting and re-laying or swapping ridge tiles, against £200 to £400 for repointing a ridge or hip. The difference reflects the work: repointing treats the joints, while re-bedding replaces the support under every tile. Those are national figures. Your own price follows the survey, and the written quote covers access, labour, mortar, fixings and waste.
Access comes first
A ridge is the highest part of the house, so the first decision is how to reach it safely. On a low bungalow, a roof ladder and edge protection may be enough. On a three-storey terrace on one of the steep Stroud lanes, a scaffold is normally the safer way to work, and we plan for it in the quote rather than discover it on the day.
Taking the ridge off without losing the line
The old ridge is removed one tile at a time, working from one end. Before the first tile comes off, we note how the ridge finishes at each end and how the tiles are lapped, so that the new run matches the old. Each tile is lifted, knocked free of its mortar and stacked on the scaffold or in a bucket lowered to the ground. Dropping mortar from a ridge into the gutters is a common cause of blocked outlets, so the rubble goes into bags or buckets, not down the slope.
Sorting what can be reused
Each tile is checked as it comes off. Hairline cracks, frost damage along the edge and chipped ends all rule a tile out, because a damaged tile will not sit flat on a new bed. Sound tiles are kept in order. Where tiles have to be replaced, we match the profile and colour as closely as the stock allows, and we show you the photographs from the roof so you can see which were rejected and why.
Profiles vary: half-round, angled, and decorated crested types. A replacement of the wrong shape sits badly against its neighbours and the join shows from the lane. Matching takes effort, and on older roofs it is part of keeping like for like.
What lies underneath
With the ridge off, the top of the roof is exposed for the first time. We look at the ridge board or the tops of the rafters, the battens that finish the slopes on either side, and the underlay where it meets the ridge. If the underlay has perished or been cut short, it is renewed. If the timber beneath is soft, the job has changed, and you hear about it before any more work goes on.
Cleaning the bed and checking the timber
Old mortar left on the roof is the most common reason a re-bedded ridge fails early. New mortar will not grip a surface that is still holding a crust of the old one, and a tile set on a lumpy base rocks. So the whole line is cleared back to the roof tiles on either side and to the timber at the top.
Clearing the top courses
The uppermost course of tiles on each slope is cleaned of debris, moss and loose mortar. Any tile in that course that is cracked or slipped is replaced now, because it will be covered by the new ridge and will not be reachable again without lifting everything. The batten at the top of each slope is checked and, if it has rotted or split, replaced.
Ventilation at the ridge
Some roofs breathe through the ridge, with a gap under the tiles that lets damp air from the loft escape. BS 5250 guidance, as set out in Marley's advice, calls for continuous high-level ventilation in some cases, including roofs steeper than 35 degrees. If the roof needs a vent at the top, the new ridge has to leave room for it rather than seal it. We raise this on site where the loft shows signs of condensation.
Wetting the surfaces
Dry clay or concrete pulls the water out of fresh mortar before it has set, leaving a weak bond. Surfaces that will take the mortar are dampened first, a step that seems small and makes a visible difference to how well the new bed holds.
Mechanical fixing: why mortar no longer does the job alone
Mortar was once the only thing holding a ridge on. That changed with the 2014 revision of BS 5534, the standard for slating and tiling. Marley explains that after the 2014 revision, mortar strength alone could not be counted on, and every bedded tile or fitting should carry a mechanical fixing. The mortar stays, but it no longer resists uplift unaided.
This is the point where a modern re-bed differs from one done a generation ago. Each ridge tile is tied to the roof structure with a fixing: typically a stainless or galvanised bracket or strap that screws into a timber ridge board or batten, with the tile held down by a screw or clip. The tile is then bedded over the fixing, so the finished ridge looks the same as a traditional one while the fixing does the holding.
Why the fixings matter in practice
A ridge catches wind from several directions, and a bedded tile with nothing but mortar under it relies on that mortar staying attached. Once the bond cracks, a gust can lift the tile and drop it. A fixed tile can still crack its mortar, but it stays where it is, and the crack becomes a repair instead of a hazard on the pavement below.
Where the fixing goes
The fixing needs solid timber to bite into. That is why we expose the ridge board or the batten tops before re-bedding, rather than fixing blind into mortar. A fixing in the wrong place, or into soft wood, does the same job as no fixing at all. If a roof has no timber at the top suitable for the fixing system, the repair has to supply one, and that is part of the quote.
A re-bedded ridge pairs mortar with fixings under BS 5534. A dry ridge is a different method: a kit tested to BS 8612, the specification for dry-fix ridge, hip and verge products. Both are legitimate.
Bedding, jointing and finishing the ridge
With the surfaces clean, damp and checked, the new ridge goes on from one end. A bed of mortar is laid along the line, each tile is set into it and tapped down to its level, and the mechanical fixing is made before the mortar stiffens. The tile ends are buttered where they meet, so each joint is filled right through rather than only on the face.
Keeping the line and the level
A taut line along the top of the tiles keeps the ridge straight, and the bed is built up or cut down to bring each tile to the line. A ridge that sags between two firm tiles is one that has been laid in a hurry. If the roof itself has dipped, the ridge follows the roof, since forcing a dead-straight line over a bowed ridge board would leave thin mortar in one place and a hump in another.
The end tiles
At a gable the ridge finishes against the verge, and at a hip it meets the hips. These are the busiest junctions on the roof, and where a bed is most often missing. The end tile is bedded and fixed with care, and any gap between the ridge and the verge tiles is filled and shaped so water cannot track in behind. Our hip tile repairs guide covers the three-way junction, and the mortar verge repairs guide covers the gable end.
Pointing and cleaning down
Excess mortar is struck off, the joints are pressed and brushed to a clean finish, and smears are cleaned from the tile faces before they set. The mix is covered in our answer on the ridge mortar mix. Fresh mortar must be protected until it has set, so we avoid starting a re-bed with frost or heavy rain forecast.
Where re-bedding reaches its limits
Re-bedding repairs the top of the roof. It does not repair a roof that is failing underneath, and part of the job on site is telling the two apart.
Soft timber and moved rafters
If the ridge board is rotten or the rafters have spread, a new bed will not hold the ridge straight. We would then propose carpentry first, with the re-bed after. This is the main reason we want to see the top of the roof opened up before giving a final figure.
Slopes that are nearly finished
If the slopes below the ridge are slipping, cracked or full of patched slates, a new ridge on top of them buys a short reprieve. We would rather say so than put a good ridge on a tired roof, and give you the options for the slopes alongside. The photographs from your own survey show where your slopes stand.
Listed and conservation area roofs
A traditional ridge on a protected building may need lime and not cement, and may be stone and not clay. That is a different method with its own rules, set out in our guide to lime-bedded ridges. Where the house is listed, or stands in a conservation area, the council's planning team should be asked first.
When dry ridge is the better answer
On some roofs, particularly where the ridge needs frequent attention or where winter working is likely, a dry ridge system is worth pricing. MyBuilder puts dry ridge at £40 to £60 per metre with £500 to £1,000 for a typical job. Checkatrade gives £50 to £70 per metre, excluding VAT. We price both routes when the roof suits either, and explain what each leaves you with.
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