The short answer
You can, but you should not. Slate is brittle, and a boot placed on the wrong spot cracks it, often without any sound you can hear. The surface is also slick when damp or covered in moss or lichen, so a slip can be fast and the fall serious. Roofers use roof ladders, crawling boards and edge protection to spread their weight and stay secure. For a homeowner, binoculars or a camera from the ground are safer.
Why slate breaks under a boot
A slate is a thin sheet of rock, split along its natural grain, and it lies on the roof supported only at its top edge by a nail or hook and resting on the course below. It is not designed to carry weight in the middle or at the tail. Step on the exposed tail of a slate and it can snap across, or crack along the grain beneath your foot. On older roofs the slates may already have hairline fractures or weak nail holes, so the load is even more likely to damage them. A cracked slate often stays in place and looks fine, then lets water run through to the batten and the underlay the next time it rains.
Walking over a roof also scuffs and chips edges, shifts slates sideways and loosens nails that are already tired. The damage appears as leaks weeks later, and the person who walked on the roof never connects the two.
The personal risk
Slate is smooth. When it is wet with rain or dew, or has a green film of algae, it is as slippery as a tray. Roofs are also steep, and the edges at the eaves have a gutter that will not stop a falling body. Falls from roofs cause serious injuries, and most of them involve people who were up there for what seemed like a quick look. A ladder leaning on the guttering also puts load on a part that is not made to carry it. If you must see the roof, use the ground and a pair of binoculars, or the zoom on a phone camera, and look for slipped slates, gaps in a course, broken ridge pieces and lead flashings that have lifted.
The other safe option is a drone or a roofer's photographs. Many problems show up from below too: stains on a ceiling, damp in the loft, daylight through the covering or slates lying in the garden. Our page on the signs a slate roof needs replacing lists what to look for.
How roofers work on slate safely
A roofer will start with scaffolding or a tower where the job justifies it, which provides a stable platform and edge protection. For repairs on the slope, a roof ladder hooks over the ridge and spreads the load across several courses, and a crawling board does the same for sideways movement. Slates are lifted with a slate ripper, a flat hooked tool that cuts the nails and releases the slate without disturbing its neighbours. Fall arrest harnesses and anchor points add a second layer of protection. Work only goes ahead in dry, calm weather, because wind and rain make a slate roof dangerous even for people who do it every day.
Every step of a repair is planned to avoid putting weight on slates that have not been checked. Our explanation of how a single slate is replaced shows the method in detail.
Solar panels, aerials and gutters
Many roof visits are for jobs that look small: fitting an aerial, clearing a gutter, adding solar panels, repointing a ridge. Each one means standing on or near the slates. Anyone doing the work should use proper access and leave the covering as they found it. If a tradesperson has been on your roof for another purpose, ask them to check for broken slates when they come down, and keep a record of what they say. A stack of broken slates in the garden after a job is a sign something went wrong.
Where slates have already been cracked by foot traffic, replacing them is usually a small repair. Left alone, they let water in and attract a bigger bill. Our guide to slipped and cracked slates explains the repair options.
Winter, frost and wet slate
Conditions change the risk a great deal. Frost leaves a thin, nearly invisible film of ice on slate that is slick as glass, and it can last in the shade long after the sun has warmed the rest of the roof. Autumn leaves, wet moss and fallen blossom make the surface just as treacherous. Even on a dry, bright day, the glare off pale slate can hide a broken piece until your weight finds it. Plan any necessary roof work for settled weather in spring or summer, and treat any visit in the colder months as a job for experienced hands only.
Gutters and ladders add to the danger. A ladder footed on soft ground or leaned against plastic guttering can slide without warning. A ladder stay or stand-off bracket spreads the load over the wall instead of the gutter, and someone should always foot the ladder from below.
When we survey a slate roof, we use a roof ladder or access equipment instead of walking directly on the covering, and we record what we find with photographs you can look at from the ground. Any repair is fixed in price before we begin. If you want a second opinion on your own roof, our slate roofing service starts with exactly that.
Every roof is different. A free survey with photos settles it for yours.
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