The short answer
It is not a good idea. Roof tiles are made to shed water, not to carry a person, and they can crack or slide underfoot. Roofers spread their weight with roof ladders and crawl boards and set up their own protection first. Asbestos cement roofs are different again: HSE guidance says they are always fragile, and nobody should step on one.
A tiled roof looks solid from the ground. Up close it is a skin of overlapping pieces, each resting on a narrow strip of timber.
Why tiles break underfoot
A tile is held at its head by a batten, the narrow timber lath it hangs from, and at its tail by the tile below. Between those two points it spans a gap. A boot placed mid-span puts a point load on a piece of fired clay or cast concrete that was designed to carry rain and wind, not body weight.
Why do tiles crack when someone steps on them?
Because the load lands where nothing supports it. A cracked tile may look whole from the ground, since the tile above covers the break. Water then runs along the crack, finds a nail hole and wets the underlay. The damage appears as a stain on the ceiling weeks afterwards, a long way from where the foot went.
Age adds to the risk. Old tiles take up water and turn brittle, frost can weaken the face and a rusted fixing can leave a tile loose. Wet moss and algae turn the surface greasy. Someone who walks a slope just to look at a problem can leave three more behind, and may end up on the lawn. Even a fit, careful person misjudges where a batten runs under a tile, because nothing on the surface shows it, and a step between battens is a step onto an unsupported span.
How roofers move on a slope
A roofer does not simply stroll across tiles. Weight is spread, and the person is held.
What are roof ladders and crawl boards?
A roof ladder is a ladder with hooks that lies along the slope and catches the ridge, the crest of the roof. The roofer climbs with weight carried on the ladder, bridging the tiles. A crawl board is a wide plank laid across the slope as a working platform, so one person's weight is shared over many tiles instead of two or three. Both rest on the structure rather than on single tiles, though the covering must still be sound enough to take them.
Edge protection and a safe route up come first, and we settle access at the survey. Our answer on fixing roof tiles without scaffolding explains the options and when scaffold is the safer choice. Never go up yourself for a photograph. A fall from eaves height onto a path is as serious as one from a higher roof, and a long lens does the same job. Binoculars from the garden, or a shot from an upstairs window, usually show what a roofer needs to see.
Asbestos cement is always fragile
Some garage, outbuilding and farm roofs are made of asbestos cement sheet, a corrugated or flat material widely used before 2000. HSE guidance A14 puts asbestos cement roofs in the always-fragile category.
Is it ever safe to step on an asbestos cement roof?
No. A sheet can give way under a person without warning, and the fall through it is serious. If the material is broken it can also release fibres, so damage to the roof is a health matter as well as a safety one. HSE's rule of thumb is that a building built or refurbished before 2000 should be treated as containing asbestos.
Careful removal of asbestos cement counts as non-licensed work, but substantial breaking up makes it notifiable non-licensed work. Double-wrapping and labelling come first for the waste, which then goes by consignment note, not into a skip. If you think a roof might be asbestos cement, our garage and asbestos roofs page explains how we approach it, and the sensible step meanwhile is to leave the roof alone.
Looking at your roof without climbing it
A good deal can be learnt from the ground. Check for slipped tiles, gaps along the ridge, chipped edges, moss and stained patches on the ceilings inside.
What is a safe way to check a roof yourself?
Walk round the house after wind or rain with binoculars. Look in the gutters for tile fragments and loose grit. Photograph anything odd and note where it sits relative to a chimney or a window. In the loft, check for daylight and damp timber, and note any drip marks on the underlay. Together with the outside photos, these let a roofer arrive knowing what to bring, whether that means roof ladders, a tower or full scaffold.
Our answer on replacing a roof tile from inside explains what the loft can and cannot tell you, and the page on a cracked roof tile covers repairs. See pitched roofing for the rest. Send us your pictures. We survey from safe access, share what we see, and the price follows in writing as one total.
More on getting onto roofs
Is slate safer to walk on than tile?
Not without proper access. Slates are thin and brittle, they can slip under a boot and a split slate may not show from above. Roofers use roof ladders and crawl boards on slate too. A damp or mossy slate is slippery, so even a careful step can send you down the slope.
What should I do once a tile has already broken?
Stay off the roof and note where the damage is. Should water be coming through, set a tray beneath the drip and move belongings clear. Water coming in is dealt with by a make-safe first, using proper access, and the full repair follows once the survey has shown what else has moved.
The full picture: Pitched roofing in Taunton ยท More short answers