For most of the twentieth century a ridge was simply a row of curved tiles pressed into a line of sand and cement. If the mortar held, the ridge held. Wind, frost and a slow loss of grip have taught the trade that mortar on its own is a poor way to hold a heavy tile on the highest, most exposed line of a roof. The current standard, BS 5534:2014, asks for the parts along a ridge, hip or verge to be held by a mechanical fixing, so that a tile stays put even when the mortar beneath it has aged. This guide explains what that means in practice and how it affects repairs on a Basingstoke house.
What the standards actually say
Two documents matter here. BS 5534:2014 is the code of practice for slating and tiling. Along the ridge, hips and verges it expects mechanical fixing, which means a physical fastener connecting each tile to the roof structure or to a batten, rather than reliance on mortar adhesion. Mortar is still allowed as a bedding and a weather seal, and plenty of ridges are still built with it, but it is no longer treated as the thing that holds the tile down.
The second document, BS 8612:2018, is the one for dry-fix kits. It sets performance requirements for the products that replace mortar altogether: the ridge batten, the clips, the unions and the caps. A product tested against that standard has shown it can resist wind uplift and stay attached as a system, which is something a mortar bed cannot be tested to do in the same way.
Neither standard is a law that sends someone round to inspect your ridge. They are the benchmark a careful roofer works to, and the benchmark a building control body or a surveyor will judge a new roof against. We do not quote clause numbers on this page, because the practical meaning is simpler than the wording: every ridge tile should be held down by something other than cement.
Why mortar alone lets go
A ridge tile is a long, heavy, half-round or angled clay or concrete unit sitting on a thin line of mortar, on the one part of the roof that takes the full force of the wind. The mortar bed faces three slow enemies.
Weather is the first. A mortar bed is porous. It soaks up rain, freezes, thaws and gradually loses its grip, especially on the north slope that never dries out. The second is movement. Roof timbers swell and shrink across the year, tiles expand and contract, and a rigid bed cannot follow that without cracking. Hairline cracks let in more water and the cycle repeats. The third is simple age: lime and sand mixes that were adequate when the house was built crumble to a powder after a few decades of exposure, and the tile above is left resting on little more than its own weight.
When a tile fails it does not always fall. More often it rocks, opens a gap at the joint and lets wind-driven rain into the roof space. Our guide to the signs that ridge tiles are failing shows what that looks like from the ground and from the loft.
What a mechanical fixing looks like on the roof
The word sounds technical, but the fixings themselves are easy to picture. There are two broad ways to meet the rule, and a roof can have either.
Mortar bed with a mechanical restraint
The traditional wet ridge is kept, but each tile is also tied down. Depending on the system, that can be a stainless steel or non-ferrous fixing that runs through or alongside the ridge tile into a timber ridge board or batten, a bracket screwed to the structure and bearing on the tile, or a strap that wraps the joint. The mortar stays as the bedding and the weather seal, and the fixing takes the load. This approach suits roofs where the owner wants the traditional look of a mortared line, or where a conservation officer expects it.
Dry-fix systems
A dry ridge replaces the bed with a framework. A continuous batten is fixed along the ridge, tiles or ridge caps are clipped or screwed to it, and a flexible, often vented, roll or profiled strip closes the gap between the ridge and the roof tiles below. Because there is no wet mix, there is nothing to crack or wash out, and the line goes on in much less time. BS 8612:2018 is the benchmark for these kits. If you want the detail of how the parts go together, our page on how a dry ridge system is fitted walks through it, and dry ridge vs mortar-bedded ridge compares the two on cost and appearance.
Hips and verges follow the same logic. A hip tile has to be restrained at its lower end as well as along its length, because it sits on a slope and tries to slide. A verge, the sloping edge of the roof above a gable wall, needs its end tiles held against uplift on an edge that catches the wind from both sides. Dry verge units are made for that job, and the principle is the same: a fixing that does not depend on mortar.
Is your existing ridge compliant?
This question comes up more than any other, and the honest answer is that it depends on the age of the roof and on what has been done to it. A house built before the current standard was written was not built to it, and that is not a defect. The rule applies to new work: a new roof, a rebuilt ridge, a replacement of components. It is not a reason to rip off a sound, older ridge.
You can do a first check yourself from the ground, and a better one from the loft. From outside, look for a ridge line that sits dead straight, with even joints and no gaps of daylight. Binoculars help. Look at the colour of the mortar: pale, sandy powder and dark moss in the joints suggest it has gone soft. Check for tiles that sit out of line, or for a visible crack running along the joint between tile and bed.
From inside the loft, switch off the light on a bright day and look along the ridge for pinpricks of daylight or damp staining on the timber beneath it. Damp, rusted nail heads or a darkened ridge board point to water getting in. Do not step off the joists: a loft floor is not a floor, and boarding is rarely strong enough to stand on.
If you can see fixings on top of the ridge, such as screw heads on a cap or a line of brackets between the tiles, it is likely a mechanical system. If all you can see is mortar, the tiles may be held by nothing else. We can establish that on a free survey, because we go up and lift a sample of the mortar to see what is underneath, then photograph the result so you can see it on your screen.
| What you see | What it usually means | Likely action |
|---|---|---|
| Sound mortar, no gaps, line straight | Bed is holding, but may have no mechanical fixing | Monitor, or add restraint at the next repair |
| Cracked or sandy joints | Mortar has weathered and grip is going | Re-pointing, or re-bedding with a fixing |
| Rocking or displaced tile | Bond has failed completely | Re-bed that section, with mechanical fixing |
| Visible screws or clips on a batten | A dry-fix system is already installed | Check fixings and end caps for wear |
Repairing or rebuilding to meet the standard
When a ridge needs work, the choice runs between three levels. The lightest is re-pointing: raking out failed mortar from the joints and filling again. It is fine when the bed beneath is sound and the tiles are bonded, and it is covered in our comparison of re-pointing and re-bedding ridge tiles. It does not add a mechanical fixing by itself.
The middle level is re-bedding. The tiles are lifted, the old bed is cleaned off, and the line is laid again on fresh mortar with a mechanical fixing added to each tile. This is the work most people mean when they ask for a ridge to be done properly, and it is where the standard changes what a roofer does. A bed laid on top of old, loose mortar is not a repair, and a tile stuck back with a blob of mortar and nothing else does not meet the rule.
The heaviest level is the conversion to dry-fix, which removes the mortar altogether and installs a batten system along the ridge, hips or verges. It costs more at the start on some roofs and less on others, and it needs far less maintenance over the years. Because the standard names the dry-fix benchmark separately, a system fitted to BS 8612:2018 gives a clear answer when a surveyor asks how the ridge is held.
Whichever level fits, we recommend matching it to what the survey finds, not to a price list. A short ridge on a garage with sound tiles and slightly tired pointing may only need re-pointing. A long ridge on a main house roof with a rocking tile at the gable end is a different job.
What to ask any roofer who quotes for ridge work
A straight quote on ridge work should answer four questions, and you are entitled to ask them. What is each tile fixed to? How is the end of every run held, at the gable and at the hip? Will the old bed be removed or built over? And is anything fitted to let the roof space breathe? That last one links to ridge ventilation and condensation, because a dry system and a vented ridge often travel together.
Be wary of quotes that describe the work only as a "ridge re-point" with no detail, or that cannot tell you what the fixing will be. If a re-roof is on the table, the ridge should be specified in the quote as part of the job and not left to be sorted out on the day.
When the survey is done, our report shows photographs of your ridge, the condition of the bed and the fixings we found, and a single fixed written quote for the option that fits. If repair is enough, we say so. Where we rebuild a ridge, the workmanship is covered by our ten-year written guarantee, and the site is cleared afterwards. To arrange a visit, see our ridge tile repairs in Basingstoke page, Phone 01256 213956 or use WhatsApp to book a visit.
