Walk a row of older houses in Stroud and the ridge lines tell their own story. Some are crisp, some are patched with a darker mortar, and some have lost a tile altogether. A mortar bed on the ridge, the line where two roof slopes meet at the top, sits in the weather for decades, and it moves a little with every change of temperature. A dry ridge takes the mortar out of the arrangement.
In place of a mortar bed, a dry ridge uses a timber batten, plastic or metal fittings and screws to hold the ridge tiles down mechanically. That is the whole idea, and this guide explains each component, the British Standard that tests the products, what the system does for ventilation in the roof void, and where it is a good fit. If you are weighing it against mortar rather than looking at the product itself, our guide on mortar or dry-fix is the better place to start.
What a dry ridge is made of
Manufacturers differ in the detail, but nearly every dry ridge kit has the same four families of parts. Knowing them helps you read a quote and spot a product that has been left half-fitted.
- The ridge batten. A length of timber fixed along the very top of the roof, bridging the last course of tiles on each slope. It gives the system something solid to screw into.
- Union strips or ridge unions. Flexible or rigid strips that run beneath the ridge tiles and close the gap between the two slopes. They keep rain and wind-blown dust out of the roof void and, in many kits, carry the ventilation openings.
- Clips and brackets. They seat each ridge tile on the batten and hold the joint between neighbouring tiles at a uniform spacing.
- Screws and end fittings. Stainless or coated screws fix the tiles through the clips to the batten, and end caps finish the open end of the ridge at a gable.
Some systems add a rubberised or mesh strip along the edge of the union, which presses against the tile surface and allows for the profile of a pantile or a double Roman. Others rely on a rigid support that sits clear of the tile profile entirely. Both approaches are common; which one fits comes down to the tile profile.
Why there is no mortar
Mortar can crack, shrink away from the tile and absorb water. A dry system has nothing to crack. The tiles are held by fixings that stay put, and the gaps between neighbouring tiles are closed by the clip or the union, not by a mortar seam.
How the fixing goes on, step by step
On a new roof the sequence is straightforward. On an existing roof it starts with taking the old ridge off, which is where most of the time goes. Our survey notes the tile type and the condition of the top course first, because a damaged top course has to be dealt with before any batten goes on.
- Strip the old ridge. The tiles are lifted off and the mortar cleaned out down to the top course and the ridge timber beneath.
- Check the top courses. The last course of tiles on each slope must be sound and correctly lapped. Cracked or slipped tiles at the top are replaced, because they are what the system sits on.
- Fix the batten. The ridge batten is screwed through into the rafters or the ridge board, as the manufacturer's instructions state.
- Lay the union. The union strip is set along the batten and pressed down onto the tile surface on both slopes.
- Fit clips and tiles. Each ridge tile is seated on its clip and screwed down, working from the end of the run that is furthest from the prevailing wind where the roof allows it.
- Finish the ends. End caps or a mortared bonnet tile close the ridge at a gable or at the junction of a hip.
One thing that surprises owners is how little of a dry ridge is visible. From the ground it can look nearly the same as a traditional bedded ridge, with a neat, regular line and no mortar joints. That is deliberate. A system that is easy to recognise from the road is usually one with exposed plastic parts, and most products now hide theirs.
The top course of tiles is what a dry ridge rests on. Fitting a new ridge over a loose or cracked top course just moves the leak.
What BS 8612 tests
BS 8612 is the standard that dry-fixed ridge, hip and verge parts are tested against. Marley, the tile maker, says a product that has not been through that testing cannot be used to show compliance. In practice, that means the standard gives you a way to tell a system that has been proven under load from one that simply looks the part.
BS 8612 does not replace BS 5534, the British Standard for slating and tiling. It sits beside it. Since the 2014 revision of BS 5534, ridge, hip and verge fittings are expected to be mechanically fixed rather than depending on mortar alone, and BS 8612 is the yardstick for the dry products that do that job. Our guide to BS 5534 and BS 8612 sets out how the two documents relate and how a compliant mortar ridge is also built.
What to ask a supplier or installer
- Is the product tested to BS 8612, and can you see that stated in the data sheet?
- Is it tested with the tile you have, not a similar one? Systems are matched to tile profiles.
- Are the fixings the ones the tested system specifies? A different screw is a different system.
The edition year of BS 8612 is not stated on the manufacturer page we rely on, so we do not quote one. If a data sheet cites an edition, that is the one to hold the product to.
Not every dry product is the same
The word dry covers a wide range of kits. Two systems can both be called dry ridge and differ in the batten, the fixings and the way the union is supported. A cheap kit with no test behind it is a different proposition from a tested one, and the price difference is usually modest next to the cost of the scaffold you need to fit either.
Ventilation and the roof void
A ridge is also the highest point of the roof void, and the highest point is where warm, moist air collects. BS 5250 covers managing moisture in buildings, and Marley's published cold-roof guidance draws on it. The answer changes with underlay and pitch, so no single figure covers every roof.
Marley's guidance says that with a breather (low-resistance) underlay and a well-sealed ceiling, a 3 mm gap from ordinary eaves construction can be enough, or alternatively 5 mm of ventilation at high level. For a non-breathable underlay, it asks for ventilation at the eaves and, in some cases, a continuous 5 mm opening at the top: where the pitch is over 35 degrees, where the span is over 10 m, or where the roof is a lean-to or single-slope design.
What a dry ridge adds
Some dry ridge unions have built-in vents; others are closed. A vented union can provide the high-level opening that the guidance describes. A closed one gives none, which can be fine on a roof that does not need it and wrong on one that does. We check on the survey what ventilation the roof already has, then choose a union to suit, and we do not assume a dry ridge improves a loft's airflow. The manufacturer's data sheet states the opening area of its own vented product.
Ventilation is a property of the whole roof, not the ridge alone. Eaves, underlay, ceiling and ridge work together, and blocking one of them can cause condensation in the others.
If you are curious about vented ridge options in particular, we cover them in the ridge and verge section of this site, and the answer depends on your loft, not on a rule of thumb.
Which roofs a dry ridge suits
Dry ridge is made for roofs covered in interlocking or plain concrete or clay tiles. Systems are produced for plain tiles, pantiles and the double Roman profile, and each has a fitting range designed for it.
Where it is a strong choice
- Exposed ridges. Where a mortar ridge keeps cracking or losing tiles, a mechanical system removes the failing element.
- Long runs. A long, straight ridge on a modern estate house suits a kit that goes down quickly and uniformly.
- Repeat repairs. If a ridge has been re-bedded and has failed again, a dry system is a sensible next step.
Where it needs thought
- Old roofs with irregular ridge lines. Hand-made clay tiles and a ridge that has sagged over the years may not suit a straight, rigid batten without packing or adjustment.
- Stone and heritage roofs. A traditional dressed-stone ridge on a Cotswold stone roof is a different matter. Appearance and the conservation rules matter more than speed, and our heritage ridge work is covered separately.
- Natural slate. Dry fix does exist for slate, and the profile of a slate ridge needs a specific product.
Within the Stroud valleys the mix of roofs is wide: stone-tiled cottages, Victorian terraces in slate and interwar and modern houses in concrete or clay tile. The ridge should suit the roof under it. We look at your own roof on the survey and photograph the ridge before we recommend either method.
Cost, guarantee and what happens on site
MyBuilder's dry ridge guide, updated in August 2026, gives £40 to £60 per metre as the typical UK rate, with a whole job usually £500 to £1,000. Checkatrade's roof repair guide, headed October 2026, quotes £50 to £70 per metre ex VAT. Both are national figures rather than Supreme prices, and neither includes scaffold. Our full guide to ridge, hip and verge repair costs sets them beside the mortar options. Scaffold alone can be a large cost on a steep Stroud lane, which is worked into the written quote after the survey.
On the day
The ridge comes off, the top course is checked, the system goes on and the debris goes into a skip or a bag lowered to the ground. We do not leave the old mortar on the roof or in your gutters. Taking the old bed off sheds fine mortar dust, and we clear it from the roof and gutters before the job is signed off.
After the work
You receive photographs of the finished ridge from the survey position, and the work is covered by our 10-year workmanship guarantee in writing. A guarantee on workmanship is not the same as the manufacturer's product warranty, and the two should not be mixed up. Ask for the manufacturer's own terms if you want those as well.
To get a figure for your own roof, ring 01453 933613, send photographs of the ridge and the top slopes through WhatsApp, or fill in the enquiry form. The survey then looks at the rest. The wider ridge and verge service page lists the other jobs we do up there.