How Is an Asbestos Cement Garage Roof Safely Removed?
An asbestos cement garage roof is removed safely by dampening the sheets with a surfactant spray to hold down surface dust, unbolting or cutting the metal hook bolts from the purlins without cracking the cement, lowering each corrugated sheet down whole, and wrapping it immediately in heavy-duty 1000-gauge polythene or UN-approved hazardous waste bags.
Why Corrugated Cement Roofs Need Careful Handling
Across Hampshire—particularly on detached rural outbuildings around the Test Valley and post-war domestic garages—corrugated cement sheets were the standard roofing material right up until the late 1990s. Most of these sheets contain between 10% and 15% chrysotile (white asbestos) locked into a dense Portland cement matrix. Occasionally, older sheets installed before the 1970s also contain crocidolite (blue) or amosite (brown) fibres.
Because the fibres are tightly bound into the cement, an intact roof does not constantly shed fibres into the air. The hazard starts the moment the sheets are snapped, dropped from height, power-washed, or cut with an angle grinder. After forty or fifty winters of frost, lichen, and rain, the cement surface erodes and becomes brittle, meaning a sheet can crack under its own weight if lifted poorly.
At Asbestos in Homes (operated by BPS), we dismantle corrugated garage roofs, lean-to covers, and cement rainwater goods every week. If you are not sure whether your garage roof contains asbestos—later fibre-cement replacements look almost identical once covered in moss—we can take a discrete corner sample first and run it through an independent UKAS-accredited testing laboratory before you commit to full removal.
Honest Trade Judgment: When to Leave It Alone vs When to Strip It Off
Not every asbestos cement garage roof needs tearing down immediately. When we inspect an outbuilding, we look at the underside of the sheets and the state of the supporting timber or steel purlins before recommending removal.
When You Can Manage or Seal It in Place
- Dry underside with no cracks: If the garage is bone dry inside, the sheets have no fractures, and you have no plans to convert or demolish the building, leaving it undisturbed is often the safest option.
- Isolated bolt leaks: Sometimes water drips solely around a rusted J-bolt washer rather than through the cement sheet itself. Replacing a single perished washer carefully from above without drilling the sheet can buy another few years.
- Over-cladding limitations: We strongly advise against screwing new timber battens or metal sheets directly through old asbestos cement, as every screw point releases fibres and cracks brittle sheets.
When Full Removal Is the Right Call
- Porous, weeping sheets: Over decades, cement thins out until water soaks straight through the belly of the corrugations, rotting the timber rafters underneath.
- Split corners and frost damage: Once longitudinal cracks form along the bolt line, high winds can lift and snap a panel, dumping broken asbestos debris across your driveway or neighbour's garden.
- Planned roof replacement or demolition: Roofers and general builders will not fit a modern plastisol steel, EPDM rubber, or tiled roof until the old asbestos sheets and cement verge boards have been legally stripped and certificated.
What Happens on the Day: Step-by-Step Safe Dismantling
The whole goal of non-licensed asbestos cement removal is to take the roof apart in reverse order of how it was built—keeping every sheet intact and preventing airborne dust. Here is the exact method our operatives follow on site.
Site Setup, Drop-Zone Sheeting & PPE
Before touching the roof, we ask you to clear vehicles, bikes, and stored items out of the garage. If bulky items cannot be moved, we sheet them over completely with heavy-duty 1000-gauge polythene taped at the edges. We lay a thick polythene drop-sheet across the garage floor and set up a cordoned wrapping station on the driveway. Our team puts on Category 3 Type 5/6 disposable coveralls, non-laced footwear, and face-fitted FFP3 respirators.
Wetting Down with Surfactant Spray
Using a low-pressure knapsack sprayer filled with water and a wetting agent (surfactant) or diluted PVA solution, we thoroughly mist the upper surface of the roof sheets, the overlaps, and the mossy bolt heads. Unlike a hosepipe—which can wash contaminated moss down into the drains—a low-pressure surfactant mist soaks into dry lichen and weathered cement dust so fibres cannot lift into the breeze when sheets slide apart.
Releasing Fixings Without Breaking the Cement
We never stand directly on unsupported asbestos cement sheets—they will shatter under body weight. Working from safe access platforms, crawl boards, or internal mobile towers, we release the roof fixings. On timber rafters, drive screws are backed out carefully; on steel angle purlins, rusted J-bolts or hook bolts are either unbolted or snipped cleanly with bolt croppers after dampening the washer area. We start with the two-piece ridge cappings at the apex and work down course by course.
Two-Person Lowering, Encapsulation & Double-Bagging
A wet 6-foot or 8-foot corrugated cement sheet is surprisingly heavy and awkward in the wind. One operative frees and slides the sheet off the purlin while a second operative receives it so it is never dropped or thrown. Full sheets are laid flat onto 1000-gauge polythene sheeting, wrapped completely into sealed parcels with heavy-duty duct tape, and labelled with asbestos warning markings. Smaller pieces, ridge caps, old bolts, and moss debris are double-bagged first in a red UN-approved hazardous waste sack (carrying the official CDG hazard diamond) and then sealed inside a tough clear outer polythene sack.
H-Class HEPA Vacuuming of Timber Rafters & Wall Tops
Once all sheets, cement guttering, and verge undercloaks are off, decades of dry dust and mortar crumbs are always left sitting along the top of the brickwork and timber purlins. A domestic vacuum cleaner will blow fine asbestos fibres straight out of its exhaust filter. We clean down every rafter, wall plate, and window ledge using an H-Class HEPA vacuum cleaner and wet wipes, then roll up the floor polythene inward and place our disposable coveralls into the hazardous waste sacks before leaving site.
What Drives the Cost of Asbestos Garage Roof Removal?
When we price up a garage roof removal across Hampshire, we don't use guesswork. Hazardous waste transfer stations charge strictly by weight (per tonne or part-tonne), so four practical factors dictate the quote:
1. Total Roof Area & Sheet Weight
A standard single garage (roughly 15 to 18 square metres) weighs around 250kg to 350kg when dry, and noticeably more when saturated with winter rain and thick moss. A double garage or pitched roof with heavy ridge caps doubles the tonnage at the hazardous waste weighbridge.
2. Additional Cement Details (Verge, Soffits & Gutters)
Many older brick garages also have flat asbestos cement soffit strips under the eaves, cement undercloak bedded into the mortar on the gable ends, or thick asbestos cement rainwater downpipes. Stripping these at the same time is far cheaper than calling a team back later.
3. Access Around the Perimeter
A freestanding garage with clear driveway access on three sides is straightforward. A garage wedged tightly within inches of a neighbour's fence, overhung by mature trees, or sitting at the bottom of a stepped garden requires extra manpower to carry wrapped sheets safely to the van.
4. Condition of the Existing Roof
Intact sheets unbolt cleanly in big panels. If a tree branch has already crashed through the roof or someone has previously tried to smash the sheets into rubble, picking up and double-bagging hundreds of broken shards and vacuuming contaminated soil takes considerably longer.
Professional Disposal vs Taking It to a Hampshire Tip Yourself
Homeowners often ask if it is legal to unbolt their own garage roof and take it to the local recycling centre. While there is no law stopping a homeowner from working on their own domestic outbuilding, the practical and legal hurdles around transport and disposal catch many people out.
The Reality of DIY Disposal in Hampshire
Most local tips will turn you away at the gate if you arrive with asbestos sheets. You must check the official Hampshire DIY and chargeable asbestos waste guidance before touching a single bolt.
- • Strict site and size limits: Only selected Household Waste Recycling Centres in Hampshire have licensed asbestos skips, and you must book in advance and pay per sheet or bag.
- • Packaging rejections: Sheets must be double-wrapped and sealed in heavy-duty polythene to specific thickness standards before leaving your driveway. You are strictly forbidden from snapping 8-foot sheets in half to make them fit inside a family estate car.
- • Contamination risk: Loading poorly wrapped sheets into your own car risks contaminating your boot upholstery and exposing yourself without a face-fitted FFP3 mask or H-Class vacuum.
Professional Collection & Consignment Notes
Trade contractors are strictly barred from using municipal recycling centres. When we remove your garage roof, the wrapped sheets go directly to a licensed commercial hazardous waste transfer station under official GOV.UK hazardous waste consignment notes.
- • Full legal paper trail: You receive your signed copy of the Hazardous Waste Consignment Note showing the exact EWC waste code (17 06 05*), weight, carrier licence details, and receiving facility stamp.
- • Essential for roofers & house sales: Reputable replacement garage roofers and future buyers' solicitors regularly ask to see the consignment note to prove the old asbestos roof wasn't fly-tipped or buried in the garden.
- • Collection-only service available: If an old cement roof has already been stacked in your garden by a previous owner, we can come out simply to wrap, double-bag, vacuum the ground, and remove the stack legally.
How to Prepare Before Our Team Arrives
Empty the Garage Interior
Clear out stored boxes, lawnmowers, and workbenches so we can lay continuous 1000-gauge polythene across the concrete floor and position our internal access platforms safely.
Let Next Door Know
Seeing operatives in white coveralls and respirators on a garage roof can alarm neighbours if they aren't expecting it. Letting them know in advance that a routine, controlled removal is booked prevents worry.
Line Up Your Replacement Roofer
Once the cement sheets are off, your garage rafters will be open to the sky. Coordinate your roofer or carpenter to fit the new roof sheets the following morning, or keep a heavy tarpaulin ready overnight.
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Read Page →Need an Asbestos Garage Roof Tested or Removed?
Send us a couple of photos and rough measurements of your garage or outbuilding, or give our team a ring. We can confirm whether a quick lab sample is worthwhile or give you a clear, fixed price for intact dismantling and certificated disposal anywhere in Hampshire.