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Is an asbestos roof dangerous?
When the sheets are a risk, what never to do, and when it is safe after removal.
An intact asbestos-cement roof that nobody works on is low risk: the fibres are locked into the cement. It becomes dangerous when the sheets are broken, cut, drilled, scrubbed or pressure-washed, because that puts fibres into the air, and breathing them in can cause serious lung disease years later. That is why the 2020 regulations control how the roof is handled, and why a removal ends with an air test.
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When does an asbestos roof become dangerous?
When the cement holding the fibres is damaged. That happens in three ways: the sheets age and crack until edges crumble, a storm or a falling branch breaks them, or someone works on them. The third is the one you control.
The Asbestos Abatement Regulations, 2020 list what nobody may do to asbestos material. Regulation 24 bans cleaning or preparing the surface of asbestos cement, using compressed air on asbestos dust, and using power tools such as angle grinders to cut, grind or drill asbestos-containing material.
Can you pressure-wash an asbestos roof?
No. A pressure washer cleans the surface and strips it at the same time, which is exactly what regulation 24 forbids on asbestos cement, and it sprays the loosened fibres across the garden. The same goes for scrubbing or sanding before painting. Painting with no surface preparation is the only allowed way to paint it; the guide to painting an asbestos roof explains how.
Is it dangerous to live under an asbestos roof?
Not while the sheets are intact and left alone, and owning one is not illegal. Keep an eye on three things: cracked or broken sheets, crumbling edges and gutters, and leaks, which usually mean the sheets are failing (the leaking roof guide covers that). Check the ceiling too: many older houses have asbestos ceiling boards under the asbestos roof.
Drilling into the roof for a satellite dish, gutters or solar is the most common way homeowners disturb it, and solar panels may no longer go on an asbestos roof at all (why).
How long after asbestos removal is it safe?
It is not a number of hours; it is a test result. After Type 2 or Type 3 work, the approved inspection authority inspects the area, samples the air and checks that all the waste has gone (regulation 22). The area is cleared once the air shows fewer than 0.01 fibres per millilitre, and the asbestos clearance certificate is issued. Until then, stay out of the work area.
If the sheets are already broken, removal costs R150 to R250 per m² to strip and dispose of; the cost guide has the full breakdown.
Questions people ask
Is an asbestos roof dangerous if it is not damaged?
An intact asbestos-cement roof that nobody works on is low risk, because the fibres are locked into the cement. The danger comes when sheets are broken, cut, drilled, scrubbed or pressure-washed.
Can I pressure-wash an asbestos roof?
No. Regulation 24 of the Asbestos Abatement Regulations, 2020 says no person may clean or prepare the surface of asbestos cement, and a pressure washer does both.
How long after asbestos removal is it safe to go back in?
Once the approved inspection authority has inspected the area, the air sampling shows fewer than 0.01 asbestos fibres per millilitre, and the clearance certificate has been issued. It is a test result, not a waiting time.
Can I drill into my asbestos roof?
Not with power tools: regulation 24 bans using power tools to cut, grind or drill asbestos-containing material. Solar panels may no longer be installed on an asbestos roof.
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