Concrete and terracotta tiles are not asbestos products and corrugated cement sheeting often is. How to tell them apart, and from corrugated iron, without leaving the ground.
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Asbestos cement roofing: what to do and what never to do
A corrugated asbestos cement roof is usually safe while it is left alone. And is made dangerous by exactly the three things people most want to do to it: walk on it, clean it and cut it.
The roof is fine until someone treats it like metal
Corrugated asbestos cement roofing (the profile many Australians still call by its old trade name) is one of the most common bonded asbestos products left on houses, garages, sheds and carports. Weathered, it goes chalky and moss-grown and looks tired, and that appearance is what prompts most owners to act.
Three actions are the problem. High-pressure cleaning is the worst thing you can do to an asbestos cement roof: it strips the degraded surface and drives fibres into the air, the gutters and the soil around the house.
And it is prohibited in every Australian jurisdiction. Cutting or drilling the sheets with power tools does the same thing at close range. And walking on it is a structural danger before it is a fibre one: weathered sheets are brittle and give way, which is why falls through roofs remain a leading cause of serious injury in this work.
What is generally permitted, and often sensible, is careful painting or sealing of a roof that is still sound, which binds the surface and buys years. The rules on how that is done (preparation, no abrasion, no pressure washing) are set by state regulators. And the honest answer for most roofs in poor condition is that sealing is a delay rather than a solution.
Replacement is Class B licensed work in practice for anything beyond a tiny area, because roofs are large, elevated, and impossible to keep below the homeowner threshold. It also has a second half that people forget: the insulation, dust and debris sitting in the roof space beneath the sheets, which is a separate question with a separate answer.
Roofing guides
Why high-pressure washing is prohibited, what sealing a sound roof actually achieves. And how to tell when a roof is past the point where coating it makes sense.
Who is licensed to do it, what notification the job needs, what happens to the roof space underneath, and what a proper site looks like from the footpath.
Bulk insulation batts are not an asbestos product: what can contain asbestos above the ceiling is loose-fill, flue lagging, sheeting and old debris.
The sheets are only one part. Ridge and hip capping, valleys, barge boards and vents are separate products fixed at separate times: and worth a separate answer.
Not just "old grey sheet": what it was made of, the two shapes it came in. And why it can be hard to tell from the modern fibre cement sold today.
Concrete and terracotta tiles are not asbestos products. What still needs checking on a tiled roof: cement shingles laid to look like tiles, ridge capping and its bedding, and pressed metal look-alikes.
Guttering, downpipes, flue pipes, drainage pipe and garden edging were all cast from the same material as roof sheeting, and each is a separate question.
Fibre cement sheet sold today contains no asbestos. What changed, why the name stayed the same, and what to check if you did not buy the sheet yourself.
Why panels and asbestos cement do not mix, what an installer must do, and the options if your roof may contain asbestos.
There is no official expiry date for an asbestos cement roof. What ageing looks like and when to plan a licensed replacement.
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