Corrugated cement sheeting is one of the commonest coverings on older garages, and a good number of the sheets that remain contain asbestos. Left whole and dry, an asbestos cement roof is not an emergency. The trouble starts when sheets crack, get drilled, are scrubbed with a brush or a pressure washer, or are dropped from height, because that is how fibres escape. HSE sorts the removal of these sheets into the non-licensed category, as long as the material is handled and taken off without being broken up. This guide describes how that work is carried out on a garage, what changes if sheets break, where the waste goes and what replaces the roof. It covers the method, not the price, which sits on our separate guides.
Why so many garages still carry asbestos cement
Asbestos cement was a cheap, light and weatherproof sheeting, and it was fitted to a great many outbuildings, garages and sheds while it was in common use. The sheets are cement reinforced with asbestos fibre, pressed into long corrugated profiles that run from the ridge down to the eaves and are bolted to timber or steel purlins, the horizontal members that span between the garage walls. Because the sheets lasted, plenty of them are still on roofs today.
The material is hazardous because of what can happen to the fibres, not because the sheet is dangerous to look at. While the fibres stay locked in the cement, the roof is a stable covering. Weathering, moss growth and age loosen the surface over time. Drilling, sawing, breaking, brushing and jet washing are what release fibres into the air in quantity. That is why an old garage roof that has been left alone is a different proposition from one that has had its surface blasted clean.
Your eyes will not settle whether a particular sheet holds asbestos, although the age of the garage and a grey, corrugated, slightly rough surface raise the question. We deal with identification on our page asking is my garage roof asbestos. The practical rule is simple: if the sheets could be asbestos, treat them as asbestos until a laboratory says otherwise.
A sound sheet that stays whole and out of harm's way can be left for a time. The reasons people replace them anyway are mostly practical: the roof leaks, sheets have cracked, the garage is being converted, or the owner wants the building to be free of the material before a sale.
What HSE means by non-licensed work
HSE guidance sorts work on asbestos into bands according to the material and the way it is disturbed. For a garage roof the two that matter are non-licensed work and, within it, a subset called notifiable non-licensed work. Which one applies depends on how the sheets are handled.
On HSE's non-licensed work page, lifting off asbestos cement roof sheets sits in the ordinary non-licensed category when the sheets are treated with care and not broken into pieces. That one condition shapes the whole method: the sheets leave the roof whole, and every step is arranged to keep them so.
The category changes if the sheets are going to be shattered, which puts a lot of dust and debris into the air. HSE calls that notifiable non-licensed work: the enforcing authority is told before it begins, and extra requirements follow. A roof demolished with a machine, or one that has collapsed in a storm, can land here. So can a roof whose sheets are so brittle that most of them crumble as they come off. The classification is decided on the day by what the material does, which is a reason for a survey before a price.
What the careful route calls for is the right controls, correct disposal and people who understand the material. You can read HSE's own words on the non-licensed work page.
Confirming the sheets and surveying the roof
Before anything is unscrewed, the first job is to establish what the roof is made of. A small sample is taken and sent to a laboratory, and the result decides how the work is run. Sampling is itself a disturbance of the material, so it is done carefully, from a spot that is easy to seal afterwards, and ideally by someone who knows how to take it. Our page on an asbestos survey for a garage describes what that involves.
The roof survey runs alongside. We look at the sheets one at a time for cracks, for corners that have snapped at the fixings and for lower edges worn away near the gutter line. Next comes the way they are fixed: bolts through the crown of the corrugation, washers and caps, and the state of the purlins that carry them. A purlin that has rotted at a bearing or rusted through can put a sheet and the person removing it at risk.
Surveying also covers the parts around the sheets. Cement ridge pieces, barge boards, gutters, flues and any lean-to sections can contain asbestos too, and so can the boarding or soffits under the eaves. A roof that appears to be all one material is often two or three. The plan should say which parts are coming off, in what order and how each will be wrapped.
The last point to settle is what is stored below the roof. A garage with a car, tools and stored items beneath it needs to be cleared or covered, and any adjoining property or neighbour's garden needs to be considered. Sheets lowered on the open side, away from a boundary, are far easier to manage than sheets that must be passed over a shared wall.
How the sheets come off, step by step
The method has one aim: lift every sheet away in one piece and keep dust from forming. In practice that means a sequence.
Setting up
The work area is marked off so that no one wanders under the roof. Weather matters: removal in strong wind is avoided because a sheet can catch the air like a sail. Where a garage has a boundary on one side, access is planned so that sheets leave from the other.
Working on a fragile roof
Asbestos cement sheets are brittle and cannot take a person's weight. Anyone stepping on one risks falling through it, and falling through it also breaks it. The work is done from crawling boards laid across the purlins, from a safe access platform or from a tower, and never by walking on the sheets. That alone is a reason this is not a job for a stepladder and a lunch break.
Taking out the fixings
HSE's task sheet for this job says to dampen the fixings and remove them, or, where the sheets are bolted, dampen the bolts and cut them with bolt cutters while avoiding contact with the cement. Nothing is cut with a disc or drilled out, and the fixings go into an asbestos waste bag. Power tools that create dust, abrasives and wire brushes stay out of it.
Lifting, wrapping and lowering
The sheets are lifted clear whole, kept damp where that helps suppress dust, and passed down by hand or by a hoist to a prepared point, never dropped or sent down a rubble chute. Large pieces are double-wrapped in heavy-duty polythene, sealed with duct tape and given asbestos warning stickers, so they are never left loose on the ground. A sheet that does crack is wrapped at once, and the broken pieces are picked up by hand or damped and gathered, never swept.
Cleaning down
Once the roof is off, the area underneath, the tops of the walls and the purlins are cleaned with damp rags, including the bolt holes. Dry brushing is out. The clean-up is as important as the strip, and it is what leaves the garage ready to take a new roof.
Waste, disposal and what leaves the site
Asbestos waste is not household waste. Wrapped sheets cannot go in an open skip alongside builder's rubble; larger quantities go in a lockable skip kept for asbestos, and they do not belong at a standard recycling centre that does not take the material. They go to a waste site that accepts asbestos, in a vehicle that is suitable for carrying wrapped, labelled loads, and the journey is arranged before the roof is touched.
Disposal rules are set by the waste regulators and your council, and the arrangements vary by site, so ask the contractor which site is used. Asbestos is hazardous waste, and a contractor moving it needs a hazardous waste consignment note. B&NES recycling centres take small amounts of household asbestos only from residents who tell the council in advance. A reputable quote names the disposal route, the packaging and the person responsible for it. If a quote is silent on disposal, ask why.
Disposal is part of the cost, and it is one reason the asbestos line is separate from the new roof. MyBuilder's asbestos removal guide (2026) gives an average of about £2,000 and a general removal rate of about £50 per m² as typical UK figures, covering testing, removal and disposal in a range of jobs. We keep the numbers on asbestos removal cost and in our wider garage roof cost guide so this page can stay with the method.
One thing to avoid is dumping. Sheets left in a hedge or a lay-by are a risk to whoever finds them. If a sheet has already come down in a storm or been left on your land, keep people away from it and speak to the council about collection before you try to move it yourself.
What goes on in its place
Once the sheets are gone, the garage is a bare frame, and you choose the new covering. For a low-pitched or flat garage, EPDM or GRP on a new deck is a common replacement, since the existing purlins are not built for tiles. For a garage with a steeper pitch, profiled metal sheeting is the closest like-for-like swap and weighs far less than cement sheets, so it asks little of the walls. A tiled roof is possible where the timber frame is strong enough, though the extra weight has to be checked. We compare these on our garage roof materials guide.
The old purlins are examined while the roof is open. Where timbers have rotted at the walls or steel has rusted, they are renewed or treated, because the new covering will rest on them for years to come. The wall tops are checked for the cement bedding the old sheets sat on, and the fascias and guttering are replaced where they have failed.
Covering the sheets over rather than removing them is the shortcut some owners ask about. HSE's task sheet does list overlaying as an option, with the new sheets fixed to the existing purlins and drilling through the cement avoided. It skips disposal, yet the material stays on the building and passes the problem to whoever re-roofs next. On a garage that leaks or has tired purlins, removal and a clean start is usually the sounder choice.
Where a garage is going to become a room, the roof has a bigger job to do on insulation and fire performance, and the sequence matters. See our guide to the garage conversion roof.
Booking a survey for an asbestos garage roof
A firm answer needs someone on your roof. We visit, photograph the sheets, the fixings and the timbers, take or arrange the sample where one is needed, and set out in writing what comes off, how it is packaged and where it goes. A fixed price follows in writing, with the asbestos work and the new covering on separate lines. The survey is free.
If your sheets are intact and not leaking, we will tell you so, and you can decide whether to wait. If they are cracked or the garage leaks, we say that too. We repair where repair works, and for asbestos cement that often means a careful like-for-like fix, not a rushed re-roof. Before the visit, a photograph of the sheets from the ground and a note of any cracked corners or moss lines along the laps helps us plan the access.
Residential and commercial garages and outbuildings are both in scope across Bath and the towns within 30 road miles. You can ring 01225 285181, send a WhatsApp or fill in the enquiry form. Describe what you can see from the ground: cracks, moss, and how the garage joins the house. For the wider picture, start at garage roof replacement.