The ridge is the highest and most exposed point of a pitched roof — the apex where the two roof slopes meet. Ridge tiles cap this junction, shedding water away from both sides and preventing wind-driven rain from entering the roof void. Because they sit at the top of the roof with no tile above them to shed water on their joints, the way they are fixed and sealed is critical. Get it wrong and you will have persistent leaks at the very point that is hardest to diagnose from inside the loft.
Two Methods: Mortar Bedded vs Dry Ridge
Mortar-bedded ridge tiles (the traditional method) are set in a bed of sand-cement mortar over the ridge board or over the top course of tiles. The mortar fills the gap between the curved underside of the ridge tile and the roof surface on both sides, and the joints between individual tiles are pointed with mortar.
Dry ridge systems use a mechanical fixing — a ridge rail screwed through the batten into the rafter, with a continuous underlay roll, end caps, and ventilated or non-ventilated roll inserts — to hold the ridge tiles in place without mortar. The system is flexible, accommodates thermal movement, and does not crack.
Why Mortar Fails
Mortar ridge bedding is the single most common cause of roof failure in the UK. Here is why:
- Thermal movement: ridge tiles heat and cool dramatically through the seasons. Clay and concrete expand and contract; mortar does not flex and eventually cracks.
- Freeze-thaw: water enters hairline cracks, freezes, expands, and widens the crack. After several winters, the mortar crumbles or detaches entirely.
- Poor original specification: many post-war roofs used a weak 4:1 or 5:1 sand-cement mix without plasticiser, which degrades faster than the tiles themselves.
- Sulphate attack: on older chimneys with poor mortar, sulphates leach into adjacent ridge mortar and cause it to expand and crack.
A well-laid mortar ridge on a sheltered roof might last 15–25 years. On an exposed site, 10–15 years is more realistic. Most UK homes need their ridge tiles re-bedded at least twice during a roof’s lifetime.
Ridge Tile Types
| Type | Profile | Best Use | Supply Price (each) |
|---|---|---|---|
| Half round | Semicircular | Universal, most common | £4–£12 |
| Third round | Slightly shallower arc | Matching older roofs | £5–£14 |
| Angle ridge | Flat-sided, angled | Interlocking concrete tiles | £6–£15 |
| Segmental | Narrow, elegant | Thin natural slate roofs | £8–£18 |
| Hip tile | Curved, for hip junctions | Hip roofs | £10–£25 |
Clay ridge tiles tend to outlast concrete by 20–30 years and are preferred on natural slate or clay tile roofs. Concrete ridge tiles are more affordable but can look mismatched on a natural slate roof and will eventually suffer from surface erosion.
Cost: Re-Bedding vs Dry Ridge
Re-Bedding Mortar Ridge Tiles
Re-bedding involves chipping off the old mortar, cleaning the tile bedding area, applying new sand-cement mortar (typically a 3:1 mix with a proprietary additive), and re-pointing all joints. Existing ridge tiles can usually be reused if they are undamaged.
Cost table (supply and fix, ex-VAT):
| Job | Cost |
|---|---|
| Re-bed ridge tiles, per tile (reusing existing) | £8–£18 per tile |
| Re-bed ridge tiles, per linear metre | £25–£50/m |
| Supply and bed new clay half-round ridge tiles | £18–£35/m |
| Supply and bed new concrete ridge tiles | £12–£25/m |
| Full ridge re-bed, semi-detached (8–10 m ridge) | £400–£900 |
| Add scaffolding (if required) | £500–£900 |
Dry Ridge System
A dry ridge system replaces mortar with mechanical fixings. The components are: a continuous ridge roll (neoprene or foam rubber underlay), a stainless-steel or aluminium ridge rail screwed to the batten, and foam end caps (open or closed-cell, ventilated or sealed). The ridge tiles clip or sit over the rail and are secured with screws or clips through the tile.
Cost table (supply and fix, ex-VAT):
| System | Supply (per metre) | Installed (per metre) |
|---|---|---|
| Standard dry ridge kit (aluminium rail) | £8–£16/m | £20–£38/m |
| Premium stainless-steel dry ridge | £14–£22/m | £30–£50/m |
| Ventilated dry ridge (with airflow insert) | £10–£20/m | £25–£45/m |
| Full dry ridge conversion, semi-detached | — | £350–£700 |
Dry ridge typically costs 10–20% more than mortar re-bedding upfront but eliminates repeat re-bedding costs of £400–£900 every 15–20 years.
Ventilated Dry Ridge: A Building Regs Consideration
One benefit of a dry ridge system that is easy to overlook is ventilation. Traditional mortar-bedded ridges are solid; dry ridge kits can incorporate a ventilation strip along the full length of the ridge, allowing warm moist air to escape from the roof void at the highest point. This is the most effective position for roof void ventilation.
Under BS 5250:2021 and Approved Document C, cold roofs must be cross-ventilated. For rafters longer than 5 m, high-level ventilation at ridge level (equivalent area of 5 mm continuous gap per metre run) may be required in addition to eaves ventilation. A ventilated dry ridge system satisfies this requirement at minimal additional cost.
If you are re-roofing completely (stripping back to bare rafters and re-tiling), fitting a ventilated dry ridge at the same time makes strong practical sense and will be required on any compliant re-roofing project under current Building Regulations.
When to Repair vs Replace
Repair (re-point individual tiles):
- Only one or two tiles are loose or cracked
- Surrounding mortar is sound and well-adhered
- Roof is less than 10 years old
Re-bed the full ridge:
- Mortar is crumbling along more than 30% of the ridge
- Multiple tiles are rocking or have been displaced in wind
- Moss and lichen are growing into the mortar joints (sign of chronic moisture)
Convert to dry ridge:
- You are re-roofing the whole slope anyway
- The ridge has been re-bedded twice or more in the past 30 years
- The property is in an exposed location (coastal, hilltop, or open countryside)
- You want to add ridge ventilation
Finding and Vetting a Roofer
Ridge tile work is one of the most commonly quoted jobs in roofing, and unfortunately one of the most prone to unnecessary or shoddy repairs. Before instructing any work:
- Get at least three written quotes specifying whether the work is a re-bed, re-point, or dry ridge conversion
- Ask the roofer to show you photographs of any loose or cracked tiles before work begins
- Confirm whether scaffolding is needed — ridge work on a two-storey roof requires safe working platforms under current HSE guidance (Working at Height Regulations 2005)
- Check NFRC membership or equivalent trade body
- Ensure they provide a written guarantee — reputable roofers typically offer 5–10 years on mortar bedding and 20–25 years on dry ridge systems
[!warning] Doorstep Offers Ridge tile repair is one of the most common triggers for unsolicited doorstep approaches, particularly after storms. A stranger who knocks claiming your ridge tiles are “about to fall off” is almost never acting in your interest. Commission an independent inspection from a NFRC-registered roofer before agreeing to any repair from a cold caller.
Matching Existing Tiles
If re-bedding or replacing individual ridge tiles, colour and profile matching matters. Ridge tiles fade over time, so a new tile in the same product code can look obviously mismatched against weathered tiles. Options:
- Source reclaimed ridge tiles from a salvage yard that closely match the existing colour and profile
- Replace the full ridge length so the new colour is consistent
- Ask your roofer to source “pre-weathered” tiles from specialist suppliers — some manufacturers offer aged finishes for exactly this purpose
