The short answer
You cannot tell by looking, so presume asbestos until a test says otherwise. HSE tells owners to presume it in anything from before the year 2000, new or refurbished then, and a modern sheet of fibre cement is hard to tell apart from an old one. A survey with a laboratory result settles the question before anyone drills, cuts or walks across the roof.
Grey corrugated sheets on a barn, unit or garage look alike whatever they contain. The age of the building and a proper test matter far more than the look.
Why the eye cannot settle it
Fibre cement is cement reinforced with fibres and pressed into flat or corrugated sheets. For decades the fibre in many sheets was asbestos, which is why older sheets are called asbestos cement, or AC. After years of weather, a sheet with asbestos and a sheet without it share the same dull grey, the same moss and the same pattern of ridges.
Can a roofer spot asbestos from the ground?
Not reliably, and a sensible roofer will say so. The profile, the colour and the lichen hint at age and little else. Guessing wrong one way costs you money for a test you did not need. Guessing wrong the other way puts dust into the air over your staff, your yard and the neighbouring plot.
For that reason our first look at an old industrial or farm roof is a visit, not a cut. We note the sheet profile, how the sheets are fixed, the condition of the edges and any patched bays, and then we move to the question of testing. Until a result is back, our crew works from the ground and from the edges only, and we would ask any other trade on the building to wait for the result as well.
The date on the building is the best clue
HSE's guidance for duty holders is that a building dating from before 2000, new at that point or refurbished at that point, should be presumed to hold asbestos. Somerset Building Control makes a similar point about older buildings, saying that in those built before 2000 asbestos fibres are likely to be encountered during work.
What if the building grew in stages?
Commercial roofs usually have a history. A unit might have been put up in the 1970s, extended in the 1990s and re-sheeted in part more recently. Each bay can belong to a different decade, and a modern bay beside an old one proves nothing about its neighbour. Ask the owner, the previous owner or the agent for drawings, old invoices or an existing management survey, then match the dates to the bays you can see.
If the paperwork has gone missing, the safe reading is the same as for an unknown date: presume asbestos, keep people off the roof and book the survey. HSE also calls AC roofs fragile every time, which means no one crosses sheets of any age without crawling boards and proper edge protection. That includes a surveyor, a roofer and the owner who only wants a quick look at a stain.
How a sheet is tested
A survey is the route to a firm answer. Small pieces are cut from chosen sheets by a competent surveyor and go off to a laboratory, and the report records whether asbestos is present and in which bays. MyJobQuote lists a typical UK price of £325 for an asbestos survey (Sep 2026), and the real figure moves with the number and size of the roofs.
Should the test come before the quote?
On an old building, yes. A price given without that answer is a guess, because the working method, where the waste goes and how long the crew is on site all change when the sheets contain asbestos. Our own roof survey produces pictures of your building and a written price for the roofing work, and the laboratory result tells us which method to price.
Resist the urge to take a sample yourself with a hammer, a screwdriver or a saw. Breaking a weathered sheet is the very act that frees fibres, and it can turn a simple job into a notifiable one. A survey is usually a small cost set against the cost of getting this step wrong, and it protects whoever works on the roof next.
What happens once the answer is asbestos
Asbestos cement is not an emergency while it is whole and left alone. HSE places careful removal of sheets, handled without breaking them up, in the non-licensed category, and sheets that have weathered without being substantially damaged are covered too. Breaking them up substantially, or dropping a roof, becomes notifiable non-licensed work, with extra duties and health records kept for 40 years.
Where does the waste go?
Never into an ordinary skip. Asbestos waste is sealed in two layers of wrapping, labelled, and moved by a registered carrier with the right paperwork riding alongside it. If the building also has asbestos insulating board, such as soffits, deal with that first, because removing it is often licensable work and the answer rests on HSE's risk assessment rules.
Our pages on the survey before roof work, the fragile asbestos cement roof and sheet disposal go further, and the full range of work sits under commercial roofing. To begin, tell us how old the building is and attach a handful of pictures shot from ground level.
Before you book a test
Is a sheet newer than 2000 safe to cut?
Not automatically. A building refurbished before 2000 may carry older sheets in one bay and newer ones in another. HSE's presume-asbestos advice turns on when the building was built or refurbished, so check the history of each part of the roof and get a survey result before cutting any sheet.
Can I leave old fibre-cement sheets as they are?
Often yes, while they are whole, dry and out of the way of knocks. They are fragile, though, and weather makes them brittle. If the roof leaks, sags or has cracked sheets, a survey and a plan for repair, overcladding or careful removal is the sensible next step for the owner.
The full picture: Commercial roofing in Taunton · More short answers