Painting and cleaning an asbestos roof: what is allowed
A weathered asbestos cement roof looks like it needs a good clean. High-pressure cleaning it is the single worst thing you can do to a house.
Corrugated asbestos cement roofing goes chalky, grows moss and looks tired long before it stops working. That appearance is what prompts most owners to act. And it is why this page exists: the two obvious responses are cleaning and painting, and one of them is prohibited.
High-pressure cleaning: never
Do not water-blast an asbestos cement roof. It is prohibited across Australian jurisdictions, and the reason is mechanical rather than bureaucratic. Weathered asbestos cement has a degraded surface layer where the matrix has already broken down. A pressure washer strips that layer off and distributes it. Into the air, into the gutters, down the downpipes, into the soil around the house and onto neighbouring properties.
The result is not an abstract risk. It is contaminated soil around the building and fibre in the roof water system, and the clean-up costs vastly more than the roof job would have.
The same logic rules out wire brushing, grinding, sanding and any abrasive preparation.
Painting: often reasonable
Coating a roof that is still structurally sound and largely intact is a different matter and is generally permitted. A sound coating binds the surface, slows weathering and buys years.
What makes it acceptable is the method: gentle cleaning rather than blasting, no abrasion, and an approach that does not break sheets. What makes it unacceptable is the usual roof-restoration sequence applied unthinkingly (pressure wash, grind back, re-bed and re-point) which is written for tile and metal roofs.
Be clear-eyed about what painting achieves. On a sound roof it is maintenance. On a roof that is already cracked, brittle and shedding, it is cosmetic, and it can make the eventual removal harder.
Walking on it
Before the fibre question, there is a fall question. Weathered asbestos cement sheeting is brittle and does not carry weight. Falls through roofs are a leading cause of serious injury in roofing work generally, and this material is among the worst for it. If someone proposes walking the roof to assess it, that decision belongs to a professional with fall protection, not to the owner with a ladder.
Moss, lichen and gutter sludge
Gentle treatment of moss and lichen (wetting, biocide, soft washing where permitted) is very different from blasting. Whatever comes off the roof has to be caught rather than sent down the downpipe. On a house with an asbestos cement roof, treat gutter debris as potentially contaminated rather than emptying it into the garden.
When to stop coating and start planning
A few signals mean a roof is past maintenance: visible cracking across multiple sheets, broken or missing sections, sheets that flex underfoot, storm damage. Or fixings that have rusted through and left holes. At that point the honest conversation is about replacement by a licensed removalist, not another coat.
What is allowed and what is not
| Action | Verdict |
|---|---|
| High-pressure washing | Prohibited. Strips the degraded surface into air, gutters and soil |
| Wire brushing, grinding, sanding | Never. Same mechanism, at close range |
| Gentle washing of a sound roof | Generally acceptable, with the run-off contained |
| Coating or sealing a sound roof | Generally permitted, and often sensible |
| Coating a cracked or shedding roof | Cosmetic only. The conversation is replacement |
| Walking on it | Fall risk before fibre risk. Not an owner job |
Can you paint an asbestos roof, and how should it be cleaned first?
Coating a roof that is still sound and largely intact is generally permitted. A sound coating binds the surface and slows weathering. On a cracked, brittle or shedding roof it is only cosmetic.
The cleaning step is where people go wrong. Gentle washing of a sound roof is generally acceptable, with the run-off contained. Moss and lichen call for gentle treatment, and whatever comes off must be caught rather than sent down the downpipe.
High-pressure washing is prohibited, and so are wire brushing, grinding and sanding. They strip the degraded surface layer and spread fibre. Walking on the roof is also not an owner job, because weathered sheeting is brittle.
Before anyone paints your asbestos roof: questions to ask, in order
Painting only makes sense on a roof that is still sound, and the cleaning before it is where jobs go wrong. Put these questions to whoever quotes the work, in this order, before you agree to anything.
- Is the roof still sound? Cracking across multiple sheets, broken or missing sections, sheets that flex underfoot, storm damage or rusted-through fixings mean it is past coating. The conversation is then replacement by a licensed removalist.
- Who will go on the roof, and how? Weathered sheeting is brittle and does not carry weight. Expect a professional with fall protection, never an owner with a ladder.
- How will it be cleaned? The answer should be gentle washing or gentle moss and lichen treatment. If the quote mentions a pressure washer, water blasting, wire brushing, grinding or sanding, say no.
- Where will the run-off go? Whatever comes off the roof should be caught, not sent down the downpipes or into the garden.
- What happens to the gutter sludge? On an asbestos cement roof it should be treated as potentially contaminated.
- Is the method written for this roof? A standard restoration sequence of pressure wash, grind back, re-bed and re-point is written for tile and metal roofs, not asbestos cement.
If any answer is unclear, ask your state regulator before the work starts, not after.
Frequently asked questions
Can I pressure wash an asbestos cement roof?
No. High-pressure water cleaning of asbestos cement is prohibited across Australian jurisdictions. It strips the degraded surface layer and distributes fibre into the air, gutters, downpipes and surrounding soil.
Is painting an asbestos roof allowed?
Coating a roof that is still sound and intact is generally permitted and can be sensible, provided preparation involves no abrasion, no blasting and no breaking of sheets. On a cracked or shedding roof it is cosmetic rather than useful.
Can I walk on it to have a look?
Weathered asbestos cement is brittle and does not reliably carry weight, and falls through roofs are a leading cause of serious injury. Assessment belongs to someone with fall protection, not to an owner with a ladder.
When is a roof past painting?
Cracking across multiple sheets, broken or missing sections, flex underfoot, storm damage, or fixings rusted through. At that point the conversation is about replacement by a licensed removalist.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- NSW Government. Asbestos in NSW. The NSW Government asbestos portal
- WorkSafe Victoria. Asbestos. Duties, licensing and safe removal
Keep reading
- Replacing an asbestos cement roof: how the job runs
- Bonded vs friable: how to tell which one you are looking at
- Asbestos fences, sheds and garage roofs
- Roof tiles with asbestos: what a genuinely tiled roof still needs checking
- Asbestos roof tiles, sheets and “super six”: what is actually up there
- How long does an asbestos roof last? Judge the condition, not the age