Question answered
Can you walk on a flat roof?
The short answer
You can walk on a flat roof for occasional access only if the covering and the deck beneath are designed for it. Fibreglass and some single-ply systems tolerate light traffic, while felt surfaces and green roofs mark easily. Regular use needs a walkway or a purpose-built surface, and nobody should step on rooflights, near unguarded edges or on a wet or frosty roof.
Light, occasional access is fine on some flat roofs and damaging on others. The covering, the deck beneath and the edge protection decide, and some parts of a flat roof must never be stood on.
Why a flat roof is not a floor
A flat roof looks like a floor with nothing on it, but it is built as a weather skin over a structure designed to carry the roof itself, snow and wind, not a stream of people. The waterproof layer on top is thin, and it is the only thing between the rain and the ceiling.
Foot traffic damages it in small ways. Grit under a boot scuffs the surface, a heel can dent the insulation underneath, and a dropped tool can puncture a membrane. None of these show at the time, but a few seasons later the weak spot may be exactly where people usually walk.
Occasional access to clear a gutter or inspect an outlet is normally allowed for in the design of a roof. Regular use is a different design brief, and the build-up, the finish and the edges are all planned differently. The question to ask of your roof is what it was built for, not whether it looks level enough.
How the main coverings cope with feet
Fibreglass, or GRP, forms a hard, rigid shell once cured, which makes it a frequent pick for roofs that see some use. Even so, the topcoat can scuff, and the manufacturer's data sheet sets the limits. EPDM is a flexible rubber sheet that stands up to occasional access well, but sharp objects can puncture it, and it is usually protected where people step.
Torch-on felt carries a mineral-granule cap sheet that wears with repeated traffic, so paths of bare bitumen show up in the places people walk most. Liquid coatings vary with the product, and lead roofs are soft and dent easily. Planted surfaces take only light, careful access; see sedum green roofs.
Treat any claim that a roof is walk-on as a statement about a specific system in specific conditions. Ask which product, what thickness and what level of traffic it was tested for before you rely on it.
Walkways, pads and proper terraces
Where people do need to go on a roof regularly, the usual answer is to give them a path. A walkway of purpose-made pads or boards spreads the weight and takes the wear, leaving the membrane beneath untouched. The route is planned to lead to the outlets, the rooflights and any equipment that needs regular attention.
A seating area is more than a larger walkway. A roof terrace needs a build-up that carries the loads, a surface that drains, edge protection at a safe height and sometimes a different insulation arrangement. That is a design job, and we would talk it through at the survey before pricing anything.
The same issue arises on a dormer. A small roof reached through a window gets walked on to clean the glass or the gutters, so the page on replacing the flat roof on a dormer shows how access is planned for it.
Safety on a roof
The risk to you is greater than the risk to the roof. A fall from a flat roof edge can be serious, and edges are often unguarded. Rooflights and lantern lights are glazed and must never be stood or leant on; some are fragile, and the failure can be sudden. Wet felt, moss and frost make a surface slippery, and ladders add their own hazards.
If someone has to go up, keep well back from the edge, stay on a marked route, avoid rooflights altogether and stay off on wet, icy or windy days. Never go up alone. For anything beyond a quick look, it is better to have the work done by people with edge protection and the right equipment.
Regular access also raises Building Regulations questions, such as guarding and the loads on the structure. Our guide to flat roof building regulations sets out the framework.
Inspecting a roof without climbing on it
You can learn a great deal from the ground and from upstairs windows. Look for pools of water lying a day after rain, splits or lifted edges, moss in the corners, blocked outlets with leaves visible and any bubbling or cracking of the surface. A ceiling stain below is the other early sign.
If you do have to go up, put a plank or board down to spread the weight rather than stepping on the bare surface. Do not scrape or pick at anything, and do not seal what you find; take photographs instead and send them over.
We survey flat roofs from the roof and from the inside, with the right access, and photographs from the visit show you the same things we see. What we then recommend is the lightest repair that deals with the cause, with the reasons set out. Other flat roof questions are answered on our flat roofing page.
Foot traffic on flat roofs: more questions
Can I put a deck or patio furniture on my flat roof?
Not on a roof that was built as a plain weatherproof covering. Loads, falls, drainage and edge protection all change when people use a roof, so it needs designing as a terrace before anything is placed on it.
Is it safe to step on a flat roof skylight to clean it?
No. Glazing in a rooflight can fail under a person's weight with little warning. Clean it from a stable position inside or from a platform designed for the job, and keep off it altogether.
Tell us about your roof
Describe what is happening and we will call you back to arrange a visit.
- Photographs of what we find
- A written quote with one total price
- Or call 01903 299063
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