Asbestos roofs: maintain, seal or replace?

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Asbestos cement sheeting was used for roofs in many Queensland buildings before 1990 (WorkSafe Queensland (opens in a new tab)), including the corrugated profile often called "Super Six". WorkSafe also says that on buildings constructed before 1990 it's likely asbestos is present in roofing and other building elements (WorkSafe incident alert (opens in a new tab)).

First, the one thing you must not do

Don't water-blast it. It's illegal to use a high-pressure water cleaner on asbestos cement roofs, and homeowners can be fined up to $10,000 plus clean-up costs (state asbestos site (opens in a new tab)). WorkSafe says high-pressure water destroys the binding matrix of the sheeting and that the fibres can contaminate surrounding surfaces, gardens and lawns for years if not cleaned up. In 2022 it reported several Brisbane cases where painters spread asbestos debris across neighbouring properties this way (WorkSafe (opens in a new tab)). If a painter or roofer suggests pressure-cleaning before painting, don't let them.

Option 1: leave it and keep an eye on it

The state site notes that well-maintained asbestos cement roofs aren't a health risk unless they're physically disturbed. If the sheets are intact and you've no plans to work on them, leaving them is a legitimate choice. Check after hailstorms and big winds, and see Storm-damaged asbestos if sheets crack or break.

Option 2: seal or paint it

Instead of cleaning the roof, the state site suggests applying a fungicide and a sealant. WorkSafe notes there are primers, fungicides and paints made for this type of roof, and that sealing is the least effective way to control fibre release compared with removal or enclosure. Ask a paint store or roof coating supplier for suitable products, and make sure whoever does the work knows the roof contains asbestos.

Option 3: replace it

Replacement means removing the old sheets and putting on a new roof, usually metal. Things to know:

• Licensing. A roof will almost always be more than 10 m² of asbestos. A business removing more than 10 m² of non-friable asbestos needs a Class B (or Class A) licence. A homeowner needs an approved certificate to remove that much themselves (WorkSafe (opens in a new tab)).
• Working at height. The usual advice to wet asbestos down before removal doesn't apply where that would be dangerous, such as on a roof (state renovation tips (opens in a new tab)). Roof work also carries a fall risk. Both are good reasons to use a licensed removalist for a roof.
• Gutters and ceiling space. Ask how the removalist will deal with debris in gutters and the roof space.
• Clearance. Ask whether a clearance inspection and certificate will be provided after the job (state asbestos site (opens in a new tab)).
• Heritage and character areas. In some Toowoomba areas, changing a roof's look can trigger planning rules. Check council's heritage and character guidance (opens in a new tab) before you choose a new roofing material. See also Asbestos in Toowoomba.

Questions to ask

1. What's your asbestos licence class and number?
2. Has the roof been tested, or are you treating it as asbestos?
3. Does the price cover removal, gutter and roof-space cleaning, transport, disposal and clearance?
4. Who supplies and installs the new roof, and are they licensed for it?
5. How will you protect my neighbours, my water tank and my garden during the work?

For pricing and the removal process, see Bonded asbestos removal.