On 20 August 2026, WorkSafe New Zealand issued a safety alert reminding anyone planning high-pressure water spraying or compressed-air work on roofs to treat asbestos as a live risk until it is ruled out. The trigger was not theoretical. WorkSafe has been notified of multiple cases where waterblasting hit asbestos-containing roofs; the most recent involved a 1970s residential property with decramastic tiles.
After the work, debris was found across the property and inside the home. Testing confirmed chrysotile in the tiles and asbestos-containing material contaminating indoor and outdoor areas. Specialist assessment followed. Remediation was required.
For surveyors, removalists, roofers, cleaners and property managers, the alert is a clean operational reminder: the method is the hazard, and the asbestos regulations already prohibit it.
What went wrong
Decramastic roofing installed before asbestos was phased out of New Zealand building products may contain asbestos. High-pressure water and compressed air strip, pulverise and spread that material. Once fibres and debris leave the roof plane, you are no longer dealing with a roofing job. You are dealing with contamination of living spaces, yards and neighbouring areas.
WorkSafe's point is blunt. High-pressure water spraying, including waterblasting, must not be used on asbestos or ACM. Compressed air must not be used on asbestos either. Both are specifically prohibited under the Health and Safety at Work (Asbestos) Regulations 2016. The alert exists because people are still doing it on older roofs without checking first.
How this sits with the refreshed guidance
This lands a few months after WorkSafe published its refreshed asbestos guidance suite for surveyors, removalists, assessors, trades and general businesses, while the 2016 approved code of practice remains in force. The practical message is consistent across both: identify asbestos risks before work starts, especially on buildings built or renovated before 2000, and choose methods that do not create friable dust or widespread contamination.
If asbestos roofing is present, WorkSafe points operators to alternative cleaning methods that do not involve high pressure water or compressed air, including its guidance on cleaning weathered asbestos-containing roofing and cladding. If work has already started and ACM is discovered, stop and get specialist advice before continuing.
What to do on the next job
Before any roof clean, coating strip, moss treatment or similar work on a pre-2000s building in New Zealand:
- Assume ACM may be present until a competent assessment says otherwise.
- Identify and assess asbestos risk before waterblasting or any other method that could disturb roofing materials.
- If ACM is known or suspected, put controls in place before work starts — or change the method.
- Do not use high-pressure water or compressed air on asbestos roofing or cladding.
- Brief workers on the prohibition and on what to do if suspect material appears mid-job.
Property owners and PCBUs should treat a quote that leads with waterblasting on an older roof as a red flag until the contractor can show how asbestos was considered. Licensed surveyors and removalists should expect more enquiry work from facility managers who have seen the alert and want a clean paper trail before a cleaner goes on the roof.
The bigger signal
Asbestos remains New Zealand's leading cause of work-related death, with around 220 people dying from asbestos-related disease each year. A waterblaster on the wrong roof turns a maintenance task into a contamination event that is expensive, disruptive and entirely avoidable.
The regulation was already clear. The alert makes the enforcement story concrete. If your business touches older roofs, update the method statement now, not after the next complaint.