Can You Walk on a Flat Roof?

A flat roof covering is a thin waterproof layer. How it copes with a pair of boots depends on the material, its age and the weather on the day.

Is it safe to step on each type of covering?

GRP, glass-reinforced plastic, is a hard cured surface and tolerates light foot traffic well, though a sharp stone in a boot sole can scratch it. EPDM, the synthetic rubber sheet, is flexible and takes occasional walking, but it can be punctured by grit, tools and heavy loads, and some makers ask for protective walkway pads. Felt, particularly an older or sun-softened sheet, marks easily and can tear at seams and edges, so walk only where you must.

The manufacturer's data sheet for your system says what traffic it is rated for, so read it. If you do not know what covers your roof, treat it as fragile.

Frost, rain and moss make any surface slippery. A flat roof with a wet film of algae under a morning frost is a fall risk, and a fall from even a low extension can hurt. Stay off it in wet or icy conditions, and do not go up alone.

If something on the roof needs regular attention, such as a boiler flue, a satellite dish, a rooflight or an air-conditioning unit, a proper walkway is the answer. It spreads the load and protects the covering.

What does a walkway look like?

Walkways are usually made from tiles or pads of rubber or similar material laid on the covering, or from boards on supports that lift the feet clear of it. They give a clear route from the access point to the item, and they mark where to step. On a membrane roof they are fixed or bonded according to the maker's instructions, with no nails through the waterproofing.

Fitted at the time of a new roof, they cost little. Added later, they have to be fixed to a covering that is already down, which is harder. Mention anything that needs servicing at the survey, and the layout can include a route to it.

Do not walk on rooflights. Many are fragile, and others age until they will not take weight, however sound they look. Use a board across the frame, or work from a ladder or access tower instead.

Keeping gutters and outlets clear is another reason people climb up: see flat roof outlet blocked.

A balcony or roof terrace is a different structure. It has to be designed to be stood on, which brings extra requirements that an ordinary flat roof does not meet.

Can I put chairs and plants on my flat roof?

Not without checking. A roof terrace needs a deck strong enough for people and furniture, a surface that protects the waterproofing, drainage that works with paving or decking on top, and guarding at the edge where there is a drop. The build-up above the insulation is different too: paving slabs on pedestals, or timber decking on supports, sit over the covering to take the load.

Building Regulations apply to guarding and structure, and raising an edge or adding railings can change the look of the building, so planning may be involved. The page on flat roof planning permission explains the questions to ask Somerset Council. A flat roof that was built as a roof only, with weak joists and a thin deck, should not take regular use however solid it feels.

If you want a usable terrace, say so at the start. The structure, the falls and the insulation depend on it, and it cannot be bolted on later without cost.

Damage from foot traffic is accidental and avoidable. A few habits prevent it.

Who should go up on the roof?

If you need to clear leaves or check a gutter, use a ladder from the ground and a long-handled tool where you can. Where you do have to step on the roof, keep to the walkway or the edges over the walls, which are better supported than the middle of a span. Wear soft-soled shoes and no sharp tools.

Call a roofer if you see a soft patch underfoot, a spongy board, a wrinkle that was not there before, or a seam that has opened. These show the roof is already damaged, and more traffic will worsen it. Our page on whether flat roofs need maintenance sets out what is worth checking each year.

For work on or from the roof, access is arranged properly with a ladder, tower or scaffold, and the site is left tidy. Not sure what your roof is made of or what it will take? A photo from a window lets us give you a first view. The range of work is on our flat roofing page.