A single slipped or cracked tile is a straightforward repair. A scatter of slipped tiles across the whole roof usually means the nails have corroded or the battens have rotted, and patching will simply move the problem along. Loose ridge tiles are the urgent one — they are heavy, high up and, once the mortar has gone, held by nothing.
- Count the defects and note where they are. The pattern matters more than the number.
- Nail fatigue is the commonest cause of slipping, and it affects a whole roof at once.
- Loose ridge tiles are a safety issue, not just a leak risk. Treat them as urgent.
- Mortar alone has not been an acceptable ridge fixing for new work since the 2014 revision of BS 5534.
Slipped tiles: why they move
Tiles are held by a combination of their own weight, the nib that hooks over the batten, and nails or clips. When one slides down the roof, something in that chain has let go.
Nail fatigue is the most common cause on an older roof. The nails corrode over decades until they no longer hold, and the tile slides. It is a gradual, whole-roof process, which is why nail fatigue announces itself as several tiles slipping over a few seasons rather than one.
Batten rot does the same thing from the other direction. A batten that has been kept damp by a failed underlay softens until it no longer holds a nail.
A broken nib is the localised version: the small lug on the back of the tile that hooks the batten snaps, usually from frost or from someone walking on the roof. One tile, one cause, one repair.
Wind uplift lifts tiles that were never adequately fixed for their exposure, particularly at verges, eaves and ridges where the pressure is highest.
Reading the pattern
| What you see | What it usually means | What it needs |
|---|---|---|
| One slipped tile, rest of roof sound | Broken nib, or a single failed nail | Replace the tile; check its neighbours |
| Several slipped in one area | Localised batten rot or a past repair failing | Open up that area; repair battens and refix |
| Slipped tiles scattered across the whole roof | Nail fatigue — the fixings have reached their life | Patching buys time only; plan for a re-roof |
| Tiles slipping only at the verge or eaves | Inadequate fixing where uplift is highest | Refix and consider a dry verge system |
| Cracked tiles in a line | Someone has walked on the roof | Replace; access the roof properly in future |
| Widespread cracking and flaking | Frost damage to porous or end-of-life tiles | The covering is failing; assess for replacement |
| Loose or rocking ridge tiles | Mortar bed has perished | Urgent: re-bed and mechanically fix |
| Tiles lifted after a storm | Wind uplift, possibly on marginal fixings | Refix, and check the fixing spec for exposure |
The question that decides repair against replacement is not how many tiles have moved, but whether the fixings holding the rest of them are still doing their job.
Cracked tiles, and the footprints problem
Cracked tiles divide into two groups, and telling them apart is straightforward once you know what to look for.
Frost and age. Older concrete tiles become porous as the surface weathers. Water soaks in, freezes, and the tile delaminates or cracks. This shows up across the roof, worst on the shaded slope that stays wet longest, and it means the covering is approaching the end of its life.
Impact. Falling branches, debris in a storm, or — most often — somebody walking on the roof. Cracks in a line, or clustered around a chimney, an aerial or a solar panel, are usually footprints. Tiles are designed to carry water, not people, and a casual trip up to adjust an aerial can crack a dozen.
This is worth knowing when you employ anyone who needs roof access. A proper roofer works off scaffold, a roof ladder or crawl boards that spread the load. Someone who climbs across the tiles to look at a satellite dish is doing damage that will show up as a leak in two winters.
Loose ridge tiles: the urgent one
Of everything on this page, this is the one not to leave.
Ridge tiles on an older roof sit on a bed of mortar. Mortar shrinks as it cures, is attacked by frost, and eventually cracks and loses its grip. Once that has happened, a ridge tile is a heavy piece of clay or concrete sitting at the highest and most wind-exposed point of the building with nothing holding it down.
The risk is obvious and it is not theoretical — displaced ridge tiles cause serious injuries and damage every winter. There is a leak consequence too: an open ridge line lets water directly into the roof space along its whole length.
If you can see mortar missing along the ridge from the ground, or a ridge tile sitting slightly proud or out of line, treat it as a job for now rather than spring.
Dry fix, and what changed in 2014
The modern answer to ridge and verge fixing is a dry-fix system: ridge and hip tiles held by mechanical fixings with a weatherproof union, and verges finished with a dry verge unit rather than bedded mortar.
The 2014 revision of BS 5534, the British Standard for slating and tiling, means mortar alone is no longer an acceptable fixing method for ridge, hip and verge tiles on new work. Mortar can still be used for appearance, but there must be a mechanical fixing doing the actual work.
The practical consequence: if you are having a re-roof, or even a ridge re-bedded, the ridge should be mechanically fixed. If a quote proposes re-bedding the ridge in mortar alone, ask about it. It is also worth knowing that dry-fix ridges are ventilated, which helps the roof space breathe — a useful side benefit on a house with condensation problems.
When patching stops making sense
There is a point where repairing individual tiles is money into a roof that needs replacing, and these are the honest signals:
- You are calling someone out for slipped tiles more than about once a year.
- Tiles are slipping in different places each time rather than the same area.
- The underlay is visible at the eaves and tears when touched.
- Battens crumble when a tile is lifted for replacement.
- The tiles themselves are delaminating or flaking across the roof.
- Matching replacement tiles are getting hard to find.
What repairs and replacement cost
These are the roofing figures published across this site:
| Job | Typical Coventry guide price | Notes |
|---|---|---|
| Minor roof repair | from £150–£400 | Slipped or broken tiles, usually one day |
| Chimney repointing / flashing | £300–£900 | Access dependent |
| Flat roof (EPDM / GRP) | £80–£120 per m² | Warm or cold deck |
| Full re-roof (typical semi) | £5,000–£9,000 | Strip, membrane, batten, re-tile |
| Larger / detached re-roof | £9,000–£12,000+ | Scaffolding included |
A tile replacement sits at the bottom of that range. The judgement worth making is whether you are buying a repair or an instalment towards a re-roof — and we will tell you honestly which one it is.
We check the fixings and the battens, not just the tile that slipped, so you know whether this is a repair or the start of something larger.
Frequently asked questions
Is one slipped tile urgent?
Not usually an emergency, but worth dealing with before the next spell of bad weather. The gap it leaves exposes the underlay to direct weather and UV, and the displaced tile can slide further and fall. If it is above a door, a path or a conservatory, treat it as more urgent for safety than for water.
Can one tile be replaced on its own?
Yes. A roofer lifts the surrounding tiles, removes the broken one, fits and fixes a replacement and relays the others. The practical issues are matching the tile and getting safe access — which is why a single tile on a two-storey roof is not as cheap as the tile itself suggests.
What are loose ridge tiles a sign of?
Perished mortar bedding, which happens to every mortar-bedded ridge eventually. It is both a safety issue, because the tiles are heavy and at the most exposed point of the roof, and a water issue, because an open ridge lets water straight into the roof space. Re-bedding should include mechanical fixing.
Why do tiles keep slipping after being repaired?
Almost always nail fatigue. If the nails across the roof have corroded to the point of failure, replacing individual tiles does nothing for the hundreds that have not slipped yet. Repeated slipping in different places is the clearest sign that the roof needs stripping and refixing rather than patching.
Do I need to replace the whole roof if tiles keep slipping?
Not automatically, but it is the question to ask. The test is the condition of the fixings, battens and underlay rather than the tiles. If those are sound, repairs are reasonable; if the battens crumble and the underlay tears at the eaves, you are paying repeatedly for something that needs doing once.
Can I walk on my roof to look at the tiles?
No. Tiles are designed to shed water, not carry weight, and walking on them cracks them — we regularly trace leaks to a line of footprint cracks. Add the fall risk and it is not worth it. Inspect from the ground with binoculars, and from inside the loft.
Find out whether it is a tile or the fixings
We check the battens, the nails and the underlay as well as the tile that moved, so the recommendation reflects the roof rather than the symptom. Free inspection, fixed written quote.