Can you walk on a slate roof?

A natural slate is a split sheet of rock, a few millimetres thick, laid so that each one overlaps the course below. It resists rain very well, but it is brittle when pressed at the wrong spot. Standing on a slate puts a point load on it, with the unsupported tail overhanging the course below. The tail can crack across, or a hairline fracture can start from the nail hole.

Often there is no sign at all. The slate stays put, still lapped by the course above, and the crack only starts letting water through weeks or months later. What looks like a leak from nowhere may trace back to a visit by someone with a loft hatch, a satellite dish or an aerial to fix.

Older roofs are more at risk. Slates that have aged, or that are held by rusting nails, or that are simply thinner than they once were, give way more easily. A weakened slate under a skin of moss is hard to spot until it fails, and a heavy boot on a mossy slope is a good way to find one the hard way. Slate that is also wet is slippery, which adds a second reason to stay off it.

Two tools do most of the work. A roof ladder has wheels at one end and a hook at the other, so it can be run up the slope and caught over the ridge. Its rungs rest on a frame and spread the load across several slates and onto the battens beneath. A crawling board is a wide plank, with cleats, that is laid across the slope to the same effect, and moved as work proceeds.

Both give a roofer a safe place to kneel, and neither puts weight on the slates directly. They are also hooked to something solid, which is part of working safely at height, not just protecting the roof. On a long or steep slope the first step is scaffold or an access tower, and MyBuilder puts scaffold at about £1,125 on a typical full re-roof, with Checkatrade quoting £700 to £1,300.

Access is allowed for in our written quote, because it is not an afterthought on a slate roof, most of all where a steep lane or a stepped terrace leaves little room to set up.

Many problems can be found without going onto the slope. From the ground, binoculars show slipped slates, broken tails and bare nail heads. A drone survey shows the ridge, hips and valleys. MyBuilder's inspection guide lists a standard survey at £150 to £250 and a drone survey at £200 to £400, while surveys as a whole span £150 to £500.

From the loft you can see daylight through gaps and stains on the slates' undersides, the battens and the underlay. Many slipped-slate calls begin that way. When we do need to get closer, we use the ladder or board.

If you suspect a problem, please do not climb up to check yourself. Describing what is visible from the garden or pavement is the safer way to begin.

MyBuilder's slate roof guide, updated in 2026, puts a single slate repair at £60 to £120 and five to ten slates at £150 to £350. Both are typical UK figures, so a quote for your own roof may differ.

One cracked slate is a small repair. The bigger problem is that access is the dominant cost: if the roofer has to put up scaffold for two slates, the access outweighs the slates. That is why it often makes sense to do a number of repairs at once, and to deal with the more fragile slates when we are already there. Our guide to slate roof repairs covers the usual faults and how they are fixed.

A slate that has cracked cannot simply be glued. It is slid out, usually after cutting the nails with a slate ripper, a tool with a hooked blade, and a new or reclaimed slate is slid into place and held by a tingle, which is a strip of lead or copper bent up over the tail. The method leaves the neighbouring slates untouched, which is what makes it possible without walking all over them.

When we find a run of cracked or sliding slates, the cause is sometimes underneath. Tired nails and a worn underlay change what the slates can take. Read about the layer below in what underlay goes under a slate roof, and about flaking slates in why slates delaminate.

Aerial fitters, chimney sweeps, gutter cleaners and solar installers all work near the slope, and not all of them use a ladder or board. If someone has been up since your last survey and a new stain appears inside, mention it. A photograph of the underside of the slates shows what the loft can reveal.

Photographs from the survey come from your own roof, which lets you check our findings. The written quote covers the repairs, and the work carries a 10-year workmanship guarantee in writing. The wider service is described on our slate roofing page.