It might be the old garage you want to knock down, a shed roof that cracked in a storm, a barn you have just bought, or grey wall panels you have noticed on an extension. Once the word asbestos crosses your mind, it is hard to stop worrying about the garden, the kids and the neighbours. Here is the reassuring part: asbestos cement is one of the lower-risk asbestos materials when it is left intact, and there is a clear, safe way to deal with it. Find out what it is first, then choose the right option.
What are asbestos cement sheets?
Asbestos cement (AC) is cement with asbestos fibres mixed in to make it strong and weatherproof. It was used for corrugated and flat sheets on garage, shed and farm building roofs, for wall cladding and panels, and for gutters, drainpipes, ridge caps, water tanks and flues. HSE lists asbestos cement products among the common places asbestos is found in buildings built or refurbished before 2000 (HSE).
- Fitted before 2000: could be asbestos cement. Asbestos was fully banned in the UK in 1999.
- Fitted after 2000: unlikely to contain asbestos.
- Don't know: treat it as possible until it has been tested.
Can I tell by looking?
No. Asbestos cement sheets are usually grey, rigid and often corrugated, with moss or lichen on older roofs, but the fibre cement sheets made after the ban look very similar. Age, colour and profile do not prove anything. The only way to know is a sample tested by an accredited laboratory, or a survey. See survey types and indicative costs, or run the home asbestos checker if you are not sure how old the building is.
Is it dangerous?
In asbestos cement the fibres are tightly bound, which is why HSE treats it as lower risk than materials such as lagging or asbestos insulating board, and why some work on it can be non-licensed (HSE licensing). The risk comes from releasing fibres: breaking, drilling, cutting or sanding sheets, using power tools, wire-brushing, or badly weathered and damaged sheets. HSE says that for cleaning weathered AC roofing and cladding, only in exceptional circumstances is high-pressure jetting appropriate, and that needs a specialist contractor (HSE sheet A12).
Never stand or walk on an asbestos cement roof. HSE warns that AC roofs are always fragile and cannot bear weight (HSE sheet A14). Falls through fragile roofs are a serious danger in their own right.
Your options
- Leave it if the sheets are sound and you are not planning work that would disturb them. Keep an eye on their condition.
- Repair or paint it. HSE's Asbestos Essentials sheets cover repairing damaged AC and painting AC that is in good condition. HSE warns never to prepare the surface by sanding or rubbing down (HSE sheet A16).
- Overlay it. HSE's removal sheet asks whether you can overlay the sheets with non-asbestos material instead of removing them, fixing to the existing purlins and avoiding drilling through the AC (HSE sheet A14).
- Remove it once a test confirms what it is, and replace it with a modern roof or cladding.
Removing asbestos cement sheets
HSE's Asbestos Essentials sheet A14 covers removing AC sheets, gutters, drains and ridge caps on a small scale, or dismantling a small structure such as a shed or garage, as long as the asbestos cement stays intact. If the AC starts to break up and creates significant dust, HSE says the work becomes notifiable non-licensed work. The sheet does not apply to large-scale work or mechanical demolition, and it is not appropriate if other asbestos materials such as lagging or insulating board are present: HSE says to use a licensed contractor for those (HSE sheet A14).
The good practice HSE describes includes keeping people away, dampening and removing fixings rather than breaking the sheets, lowering large pieces to the ground instead of dropping them or using rubble chutes, and double-wrapping large pieces in heavy polythene with asbestos warning labels. The sheets are written for trades doing the work, so many homeowners and businesses use a competent professional who removes the sheets whole and takes the waste away legally. See all of HSE's AC task sheets in Asbestos Essentials, and read licensed vs non-licensed work.
Disposal
Asbestos cement waste must not go in your household bin or a general skip. HSE's disposal sheet says asbestos waste in England and Wales is hazardous waste when it contains more than 0.1% asbestos, so the Hazardous Waste Regulations 2005 apply and a hazardous waste consignment note is needed (HSE sheet EM9). It must go to a site permitted to take it, using a registered waste carrier. Some councils accept small amounts from householders by arrangement, so check with yours first.
Planning building work or own business premises?
If you are about to demolish, extend or refurbish, a refurbishment or demolition survey should come first. If the sheets are on non-domestic premises, the duty to manage asbestos applies: see management surveys and the asbestos register and management plan.
Don't
Don't drill, cut, break, sand, jet-wash or wire-brush sheets you have not had tested, don't walk on the roof, and don't burn or bury broken pieces. If sheets are already broken, keep people away, don't sweep up dust with a household vacuum, and read what to do if you find asbestos.
Related guides: Garage and shed roofs · Soffits · Water tanks · Flue pipes · Ceiling tiles · Where asbestos is found
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