Water-blasting an asbestos roof is illegal everywhere
ASSEA says using high-pressure water spray or compressed air on asbestos materials is against the law in every state. Queensland can fine homeowners up to $10,000 and make them pay the clean-up costs. Pressure cleaning drives fibres out of the old cement and spreads them over your yard, the neighbours' yards, footpaths, roads and stormwater drains. If a painter suggests a pressure clean first, they're the wrong painter.
Nobody should walk on it to paint it either
Safe Work Australia says roofs made from asbestos sheeting are likely to be fragile, and should be treated as fragile until a competent person confirms otherwise. ASSEA records people falling through or off asbestos roofs during maintenance. Painting one safely takes planned access, such as scaffolding or an elevating work platform, and a written Safe Work Method Statement, because work that may disturb asbestos counts as high risk construction work.
Why seal an asbestos roof at all?
Paint doesn't remove the asbestos. What a sealant can do is hold a weathered surface together, and ASSEA says weathered asbestos cement roofs release fibres more easily. ASSEA lists paint or other sealants, enclosures and capping as ways to keep asbestos materials in good condition. That's the idea behind encapsulation: sealing or covering the material so the fibres stay bound in.
Queensland's asbestos authority suggests applying a fungicide and sealant instead of cleaning. That's the heart of it: an asbestos roof gets treated, not washed.
In the ACT, WorkSafe ACT gives sealing or painting non-friable asbestos as an example of minor routine maintenance, while cleaning asbestos with high-pressure air or water isn't. That's a rule about licensing, not a sign it's a safe weekend job.
Seal it or replace it?
| Seal or paint | Replace | |
|---|---|---|
| What it does | Binds the weathered surface and tidies the look | Takes the asbestos off your roof for good |
| What it doesn't do | Fix cracked or broken sheets, or make the roof safe to walk on | Come cheap, because it's two trades and a new roof |
| Suits a roof that is | Intact, not leaking, and staying for now | Cracked, brittle, leaking or due for other work |
| Who does it | A contractor experienced with asbestos cement roofs | A licensed asbestos removalist, then a roofer |
| Down the track | The asbestos is still there for the next repair or renovation | Nothing left to manage |
Who should do the work?
Sealing isn't removal, so it isn't what an asbestos removal licence is for. In WA, Building and Energy treats roof coating as a building service, and contractors need painter registration for roof painting or coating worth over $1,000 in Perth and most country areas. Queensland's roof licence classes specifically leave out painting.
What you want is a contractor who has done asbestos cement roofs before and can explain in writing how they'll prepare it without water-blasting, scrubbing or sanding, how they'll get up there safely, and what happens to any broken sheets. Taking out a broken sheet is removal, so ask who holds the removal licence for that part.
Ask about the gutters too. ASSEA says debris in gutters under these roofs should be treated as friable, so clearing them belongs with a licensed removalist. And if the roof feeds a rainwater tank, note that ASSEA advises against using run-off from asbestos cement roofs for drinking, washing or bathing.
How a sealing job should run
Test first
Confirm it's asbestos with a sample tested at a NATA-accredited lab, so everyone works to the right rules. Our guide on whether your roof is asbestos explains how.
Check the condition
Have the roof assessed from safe access. If it's cracked, brittle or leaking, sealing is money spent on a roof that needs replacing.
Plan safe access
The contractor should explain how they'll work without standing on the sheets, and set it out in a Safe Work Method Statement.
Treat, don't clean
No pressure cleaning, scrubbing, wire brushing or sanding. Queensland's guidance is a fungicide and sealant instead.
Handle broken sheets and gutters lawfully
Broken pieces and gutter debris go to a licensed removalist, and from there to a site licensed to take asbestos.
Keep the records
Keep the test result, the contractor's details and what was applied. Anyone who works on that roof later needs to know it's asbestos.
What you can do, and what's for the contractor
You can
- Arrange testing before anyone quotes
- Look over the roof from the ground for cracks and broken sheets
- Turn away anyone offering a pressure clean
- Ask each contractor how they'll prepare the roof and work safely
- Keep records of the test and the work done
Leave to a roofer
- Every bit of work on the roof itself
- Treating and sealing the surface
- Removing or replacing broken sheets, by a licensed removalist
- Clearing gutter debris, by a licensed removalist
Our honest view
Sealing makes sense on a sound asbestos roof you plan to keep for a while, done by someone who treats it rather than washes it. We wouldn't pay to paint one that's cracked, brittle or leaking, because it'll need licensed removal anyway and the paint buys you very little. And we'd never let anyone pressure-clean it, climb on it without proper access, or talk you into doing it yourself.
Want a roofer to take a look?
Tell us the job and your postcode. We match it with a Find My Roofer certified roofer who specialises in that kind of work, and they call you to quote. Your number goes to them alone.