The ridge is the line of tiles along the top of the roof, and it takes the worst of the weather. Wind lifts it, sun and frost crack it, and for most of the last century it was bedded in a strip of mortar and left to cope. The alternative is a dry ridge: a system of fixings, brackets and flexible seals that holds the tiles in place without wet mortar. Both options are still fitted, and both can be done well or badly. This page sets them side by side, explains where the standards come in, and helps you decide which suits your roof and your budget.
What a mortar-bedded ridge is
In the traditional method, the ridge tiles are laid on a bed of sand and cement mortar, which fills the gap between the tile and the roof below. The mortar also seals the ends of the roof tiles and the joints between ridge tiles. In a good job the ridge tiles are also fixed mechanically, with a screw or bracket into the ridge board or a batten, so the mortar seals and finishes the joint and does not carry the load. In an older roof, the mortar alone did the holding.
The strength of mortar is that it is cheap, familiar and can be coloured to match. Its weakness is that it cracks. Mortar shrinks as it cures, moves with the roof timbers through the seasons, takes in water and breaks up under frost. A ridge that was sound at fitting will usually need attention in time, which is why ridge failures are one of the commonest storm callouts. Our answer on how long ridge mortar lasts goes into the timescale, and the guide to ridge bedding mortar covers the mixes.
What a dry ridge is
A dry ridge system holds the ridge tiles with mechanical fixings, usually a continuous batten at the apex and brackets or clips that tie each tile down. A flexible ridge roll or sealing strip, often with a vented section, fills the gap beneath the tile. No wet mortar is used to hold anything. Joints between tiles are closed with a fixed or sealed piece, and the ends are finished with end caps.
Dry systems arrived to solve the mortar problem, and they are now widely fitted. Their performance is covered by BS 8612:2018, which sets requirements for dry-fix ridge, hip and verge systems. Our answer on what a dry ridge system is explains the parts, and the page on how a dry ridge is fitted walks through the job.
What the standards require
The tiling code, BS 5534:2014, expects the pieces along the ridge, hips and verges to be held by mechanical fixings, so mortar on its own is no longer trusted to hold them on. That is the rule that matters most when you compare the two options, because it means a bed of mortar with nothing else does not meet current practice, however good it looks. A mortar-bedded ridge that is also mechanically fixed meets it, and so does a dry system built to BS 8612:2018.
The standard does not ban mortar. It changes its role. This is easy to misunderstand, because some marketing treats dry ridge as the only compliant choice. It is the more straightforward way to be compliant, since the fixing is built into the system. Our guide to ridge tiles and the mechanical fixing rules explains what each standard covers.
Side by side: how they compare
| Point | Mortar-bedded ridge | Dry ridge system |
|---|---|---|
| How it is held | Mechanical fixings plus mortar to seal | Fixings and brackets, with flexible seals |
| Movement | Mortar cracks as the roof moves | Flexible parts take movement |
| Weather | Water and frost break down the bed | No wet material to break down |
| Ventilation | None unless added | Many systems vent the roof space |
| Appearance | Traditional, colour matched | Close to traditional with the right system |
| Upkeep | Re-pointing or re-bedding over time | Little, apart from checks and cleaning |
| Upfront cost | Lower for a small stretch | Higher, often done as a whole |
Durability and upkeep
Mortar is the weakest link in the traditional ridge, and its life is limited. Pointing gets cracked and falls out, and the bedding underneath softens as water gets in. The ridge may stay up for a long time because the tiles are heavy, but when a gale comes it is the first part to go. Re-pointing or re-bedding is a repeat job, and each time the ridge is disturbed there is a cost for scaffold and labour.
A dry system moves that burden. The parts are made to flex, and there is no mortar bed to crack. The ongoing care is a check after storms that the fixings and end caps are intact. Dry systems have their own faults, and poor installation, cheap parts or the wrong fixing for the tile can undo the benefit. Our answer on how long a dry ridge system lasts deals with that.
Appearance and character
Many owners prefer the look of mortar, because it is what the roof had before. On a period house or in a conservation area, a mortar-bedded ridge in a colour matched to the tiles looks right, and it may be the only acceptable option. On a listed house or in a protected area, the council's conservation officer should hear about any change to the ridge detail first.
Dry systems have improved. Ridge tiles themselves are the same tiles, and the dry fixings sit underneath, so from the ground a good dry ridge is hard to tell from a mortar one. The difference shows up at the joints and ends, where the sealed or clipped finish replaces the pointed one. On clay roofs the colour match of end caps and accessories needs care, as our answer on dry ridge on clay tiles explains.
Hips and verges: the same question
The choice is not confined to the ridge. Hip tiles, which run diagonally down the roof, and verge tiles, which finish the gable edge, were also bedded in mortar and face the same rule. Dry hip systems use a hip tray and clips, with a bracket at the foot to stop the tiles creeping down, and dry verge systems clip a cap to the edge of the roof and seal the gap. Many owners decide for the ridge, hips and verges together, since the scaffold is up and the same fixings and sealing logic apply. Our guides to hip tiles and dry hip systems and dry verge systems cover those two edges.
Wind, noise and the rattle question
A common worry about dry systems is noise. Done properly, a dry ridge is quiet, because the tiles are clamped and the seals are flexible. A rattle usually points to a poorly fitted system, a part that does not match the tile or fixings that have loosened. Mortar has its own noises, mostly when it has cracked and the tile above moves on it in the wind. The strongest argument for either is the fixing: a ridge that is held on by screws or brackets into sound timber is quiet and stays put, whatever surrounds it.
Common mistakes with each
On mortar ridges, the usual mistakes are bedding the tile without a fixing, using mortar that is too strong or too weak for the tile, leaving the mix uncoloured so it stands out, and failing to clean the old bed so the new one does not bond. On dry ridges, the usual mistakes are using a system that does not suit the tile profile, fitting without a continuous batten, leaving gaps where the roll does not meet the tile and not sealing the ends. All of these are fitter errors and not product faults, and all are visible on a survey.
If you are comparing quotes, ask the roofer which one they are proposing, what holds the ridge tile on, and what happens at the ends. A clear answer is a good sign.
Cost
The cost comparison is not simple. One UK guide reports a dry ridge system on a semi-detached house at £900 to £1,600, with scaffold at £300 to £900 on top. That is a typical UK range. Once the roof has been surveyed, a fixed quote replaces it. A short stretch of mortar re-bedding can cost less than that, because you are doing less work, but there is no reliable published range for it. A long ridge, a roof with hips and a complex shape change the sums.
Think about the cost over time. A mortar ridge that needs re-bedding every so often costs scaffold and labour each time. A dry ridge costs more once and may avoid the repeat visits. Where the scaffold is already up for other work, adding the ridge costs less than it would on its own. Our guide to ridge tile repair and re-bedding costs has more detail.
Which suits which roof
Several things tilt the decision.
- Exposed site. On a windy, open roof, a dry system's flexible, fixed design suits well.
- Period or protected building. A mortar bed in a matched colour may be more appropriate, with mechanical fixing hidden beneath.
- Tight budget, short ridge. A local re-bed with proper fixings can be the economical choice.
- Repeat failures. If mortar has failed before, a dry system is the longer-term answer.
- Poor ventilation. A vented dry ridge helps a condensation-prone roof space, as the page on ridge ventilation and condensation explains.
How we advise
We look at the ridge from the roof and from the loft. We check whether the tiles are fixed or just bedded, how much mortar has failed, what the ridge board or batten underneath is like and whether the exposure of the site argues for a dry system. We photograph what we find on your roof, set out both options with a fixed written price for each, and tell you which one we would choose and why. If a small repair will do, we say so. Work carries our written ten-year guarantee, and the waste goes with us when we leave. See the wider service on the ridge, verge and dry-fix systems page.
