Asbestos Garage Roofs

Is my garage roof asbestos?

If it's corrugated cement sheet and it went up before 2000, there's a good chance it is. For the best part of 50 years, asbestos cement was the go-to material for garage, shed, stable and outbuilding roofs in Britain. It was cheap and rigid, it didn't rot, and every builders merchant sold it.

The usual look is a grey corrugated sheet, often with wide ridges. With age it weathers to a patchy off-white or green, with moss and lichen. Flat sheets were made too, and used for garage walls and side panels as much as roofs.

But looks don't settle it. After the ban, cement sheets were still made without asbestos, in the same shapes and colours. Once weathered, a modern sheet and a 1970s asbestos one can look almost the same. Looks narrow the odds. They don't answer the question.

For cement sheets on anything other than a garage, see asbestos sheets and corrugated cement roofing.

The danger nobody mentions

Almost everything written about asbestos garage roofs is about fibres. But on a garage at home, the injury that actually happens is a fall.

Asbestos cement roof sheets are a fragile material. They aren't made to carry a person, and they get more brittle every year. They don't sag or creak first as a warning. They give way all at once.

Falls through fragile roofs are one of the biggest causes of death in construction work. HSE names asbestos cement sheeting as a typical fragile surface.

That's why "I'll just nip up and fix that leak" is the most dangerous thing you can say about these roofs. A leaking asbestos roof is a job to get quoted, not a job to have a go at.

Is it dangerous if you leave it alone?

Generally, no. Asbestos cement is a firmly bound material. The fibres are locked into hard cement, and usually make up only a small part of the sheet. An intact roof on a garage isn't shedding fibres into your garden.

The risk changes when the sheets are broken up or worked on:

• Cutting or drilling with power tools. This is by far the worst thing you can do.
• Smashing sheets to get them down, rather than unbolting and lowering them whole.
• Pressure washing, scraping or wire brushing the surface.
• Sheets that are already cracked, holed, flaking or crumbling at the edges.
• Dropping sheets onto a hard surface.

A weathered roof isn't automatically a dangerous one. Moss and stains are only on the surface. What matters is whether the sheet itself is sound, and whether anything is going to disturb it. Our guide on encapsulation versus removal covers how that call is usually made.

Moss, cleaning and sealing

Lots of people want to clean up a green, mossy garage roof, or paint or seal it. Here, the obvious approach is the harmful one.

Moss on an asbestos cement roof is best left where it is. It looks untidy and holds moisture, but neither is a reason to disturb the surface. If the look really bothers you, that's a reason to replace the roof, not to clean it.

What about sealing or painting it?

Coating a sound asbestos cement roof can be a sensible choice. It's a form of encapsulation: the coating binds the surface, slows weathering and keeps the material in place. It's often cheaper than replacing the roof, and it disturbs nothing.

There are two conditions, and sealant adverts skip both:

• The roof has to be sound to start with. Coating over cracked or flaking sheets seals a problem in rather than solving it.
• The preparation mustn't rough up the surface. Everything that helps a coating stick is exactly what you mustn't do to asbestos cement. That's why it's usually a job worth getting quoted, not a Saturday project.

A coated roof is still an asbestos roof. Write down what's under the coating, because whoever takes it off in 15 years needs to know.

Do you need a licensed contractor?

Usually not, which surprises people. Work on asbestos cement in good condition is non-licensed work. No licence is needed and nobody has to be notified. The work still has to be done safely, as the law requires.

So a firm quoting for a straightforward garage roof doesn't need an HSE licence, and you shouldn't be paying extra as if they do. What they do need is to work the right way, carry the right insurance, and give you paperwork proving the waste went somewhere permitted.

For every material in a home, see do you need a licensed asbestos contractor?

Should you take it off yourself?

On this job, we'd strongly advise against it. Here's what people underestimate:

• The roof won't hold you. The sheets are fragile, get more brittle with age and give way without warning. Falls through fragile roofs are one of the biggest killers in construction. The injury happens in a second, long before fibres come into it.
• Breaking a sheet is what releases the fibres. Intact sheets on a garage aren't harming you. A cracked one being wrestled off a frame is different, and you can't see what you've released.
• Getting rid of it catches people out. It has to be double wrapped, sealed, labelled and taken to a site that will accept it. Some councils won't take household asbestos at all, and many charge. That's why a load can sit in a garage for months.
• You end up with no paperwork. A contractor leaves you a consignment note showing the waste was disposed of properly. A buyer's surveyor, a lender or a tenant may ask for it later, and you can't produce it after the fact.

It's a small job for a crew who do it every week, with the right access equipment and somewhere to take the waste. Tell us the size of the roof and where you are. We'll arrange a free, no-obligation quote, so you can see what handing it over costs before you climb anything.

Get my free quote

Does it affect what the house is worth?

This is what people ask when they're thinking of selling. The short answer: a sound asbestos cement garage roof doesn't usually change a valuation on its own. They're on a huge number of British houses, and surveyors see them all the time.

What it can do is slow a sale down:

• A buyer's survey will almost certainly flag it, because surveyors flag anything they can't rule out.
• A nervous buyer may use it to ask for money off, whether or not that's fair.
• A few lenders ask for more information when a survey mentions asbestos.

The cheap answer to all three is paperwork, not demolition. A lab result saying what the sheets are, plus a note that they're intact and in good condition, costs a fraction of a new roof. It removes the doubt a buyer is reacting to.

Taking off a sound roof just to make a sale easier is usually the most expensive fix. Buying a house? See do you need an asbestos survey on a house?

What removal and replacement cost

Single garage roof removal typically costs £400 to £1,000, plus VAT. Double garage roof removal typically costs £580 to £1,400, plus VAT. Both are prices for taking the old asbestos cement roof off, before any new roof goes on.

Taking the old roof off and putting a new one on are two separate jobs with two separate prices. Mixing them up is the most common reason a quote comes back higher than expected.

What moves the removal price

• Roof area. The obvious one.
• Condition. Sheets that come off whole are quick. Broken sheets have to be cleared as debris, which is slower and makes more waste.
• Access. Whether a vehicle can get near, and whether the roof can be reached from the ground or needs a tower.
• Disposal. How far it is to a permitted site, and what that site charges by weight. Cement sheets are heavy and bulky.
• Whether the frame goes too. Many of these garages are asbestos sheet on a concrete or steel frame. Taking down the whole garage is a different job from re-roofing it.

For your own price, get a free quote for your garage roof. Our UK asbestos removal cost report sets out what different jobs usually cost, and the cost guide explains what pushes a quote up or down. How we work out these prices.

What to put back

Once the old roof is off, the new one is ordinary building work, with no asbestos involved. The three common choices:

Check two things before you commit. Is the existing frame sound enough to take the new roof? And is the garage close enough to a boundary that the new roof needs to be non-combustible?

On an old sectional garage, the frame is often what decides whether you re-roof or replace the whole thing.

Getting rid of the sheets

Asbestos cement sheeting is hazardous waste. It can't go in a general skip, a household bin, or the back of a van to an ordinary tip. It has to be double wrapped, labelled and taken to a site permitted to accept it.

Garage roofs make a lot of waste, far more than most council allowances cover.

Some councils take small amounts free by appointment, some cap it at a few sheets a year, some charge, some run a paid collection, and some won't take it at all. You can check what your council does in our guide to 189 UK councils.

Council schemes are for small amounts that have already been taken down and wrapped. For anything more, or anything still in place, we arrange the whole job.

Already taken the sheets down and wrapped them? See what it costs to have wrapped asbestos collected.

One rule applies everywhere: asbestos removed by a contractor is business waste. It can't go through a household route, whatever your council lets residents do.