Can I re-point ridge tiles myself?

The first problem is where you would be standing

The ridge crowns the roof, the furthest point from the ground. To work on it properly you need to be astride or beside the ridge with both hands free, and that means being on the slope or on a platform high above the ground. A ladder leaned against the gutter reaches the eaves, not the apex. Getting from the ladder to the ridge means crossing a pitched surface of tiles, which can be slippery with moss, damp or frost.

Falls from roofs are a recognised danger in the building trades, and the people who do this work for a living use scaffold edge protection, roof ladders, harnesses or tower platforms for good reason. A homeowner on a leaning ladder with a bucket of mortar has none of that. Mortar is heavy, tools get dropped, and a moment's overbalancing is all it takes.

Nothing about a ridge repair is worth a hospital visit. If you cannot do it from a safe working platform, it is not a DIY job. That is the main reason, and it applies whatever your skill with mortar.

Re-pointing over a failed bed does not last

When a ridge starts to crack, the visible problem is the pointing between the tiles. Beneath that sits the bed, the layer of mortar that actually holds each tile to the ridge. If the bed has gone hollow, crumbled or lost its grip on the tile, new pointing laid over the top is cosmetic. It will look neat for a while and then crack along the same line, because nothing underneath has changed.

A proper repair means lifting the tiles, clearing out the old bedding and rebuilding. That is a bigger job than a patch, and it is the one that fixes the problem. A sealed joint that traps water behind it can also make matters worse, since the damp has nowhere to go and works into the bed from underneath.

The mix matters as well. A mix harder than the tiles can tolerate cracks early, and a mix that is too weak washes out. Choosing the right mix, and gauging it for the conditions on the day, is something a roofer learns by repeating the work.

The standard has moved on from mortar alone

For a long time ridge tiles were simply bedded in mortar. That has changed. Under BS 5534:2014, a bedded ridge or hip is expected to carry mechanical fixings too, so the mortar stops being the sole thing keeping the tiles on. In other words, even a perfect bed of fresh mortar is no longer the full job.

A DIY repair that replaces mortar with more mortar leaves the roof on a method the standard treats as inadequate by itself. The fixings, which may be clips, straps or screws into a ridge batten, have to be chosen for the tile and set in the right place. If you want to understand the difference between wet and dry systems, our guide to dry ridge versus mortar compares them.

On a listed roof, or one inside the Bath conservation area, there is a further point. Changing the ridge material or the visible detail can need consent from B&NES planning, and a patched ridge that looks different from the original could cause trouble later.

Other parts of the job people underestimate

A ridge is rarely just a ridge. These are the extras a DIY repair tends to miss.

• The ends. The last tiles beside the gable are the most exposed, and the edge details there, such as the undercloak below the end tile, have to be right. Our answer on the verge undercloak explains why.
• The hips. If your roof has hip tiles, the lowest of them relies on a small metal bracket at the foot. See what a hip iron is.
• The underlay and timbers. Water that has got past a cracked ridge may have wetted the underlay or the ridge board. Pointing hides these problems rather than fixing them.
• Matching. New ridge tiles that do not match the profile and colour of the old ones show up from the street.
• Protected wildlife. Bats and nesting birds can use roof spaces and ridge cavities, and both are protected, so disturbing a roost or a nest can be an offence.

Each of these is quick for someone who knows what to look for and awkward for someone who does not.

What we do instead and when a small job is fine

If one pointed joint has cracked and the tiles on either side are firm, a small repair is reasonable work for a roofer to do in minutes, and we will often tell you the job is that simple. If the ridge is moving, hollow or cracked along a run, we recommend rebedding it with mechanical fixings, which is the repair that lasts.

Whichever applies, the survey is free and you get photographs of the exact tiles that concern us, so you can judge the decision for yourself. Look for gaps in the bedding, ridge tiles that rock when the wind gets up, and mortar crumbs collecting in the gutter below. For a view of the whole range, the ridge and verge repairs page lists what we cover.

If you want to keep costs down, there is one thing you can do safely from the ground: look. Binoculars show gaps, slipped tiles and mortar on the lawn, and photographs of what you see help us to plan the visit. Leave the climbing to us.