How to Check Your Roof for Asbestos Before Sanding or Painting

If your home was built before the mid-1990s, there's a real chance your roof could contain asbestos — and disturbing it without checking first is both dangerous and potentially illegal. The good news is that intact asbestos roofing that is left undisturbed poses a low risk, but sanding, grinding, or pressure-washing it can release harmful fibres into the air. Here's what every NZ homeowner needs to know before starting any roof painting project.

Why Asbestos on Roofs Is a Serious Issue

Asbestos was widely used in New Zealand building materials from the 1940s through to the late 1980s, and some products were still available into the early 1990s. Fibrous cement (fibrolite) roofing sheets were a common product that often contained asbestos. When these materials are sanded, cut, drilled, or abraded, microscopic fibres become airborne and can be inhaled — leading to serious lung diseases including mesothelioma and asbestosis, sometimes decades later.

WorkSafe NZ regulates asbestos management in New Zealand under the Health and Safety at Work (Asbestos) Regulations 2016. These rules apply to both workplaces and, in many respects, to work carried out by tradespeople on residential properties.

How to Identify Potentially Asbestos-Containing Roofing

You cannot identify asbestos by looking at it — laboratory testing is the only reliable method. However, there are some useful indicators:

• Age of the home: If your house was built or re-roofed before 1994, suspect asbestos until proven otherwise.
• Material type: Corrugated or flat fibrous cement (fibrolite) sheets are the most common asbestos-containing roofing material in NZ. Metal, terracotta tile, and concrete tile roofs are very unlikely to contain asbestos, but always check if you're unsure.
• Appearance: Old fibrous cement sheets often look grey, slightly rough, and may have a weathered or chalky surface. They are not the same as modern fibre cement products, which are asbestos-free.
• Documentation: Check your LIM report, building consent records, or any original building documentation for the materials used.

If in doubt, treat the material as if it contains asbestos until you have test results.

Getting Your Roof Tested

The only way to confirm whether your roof contains asbestos is to have a sample analysed by an accredited laboratory. Here's the process:

Step 1 – Hire an Asbestos Assessor

For a roof, it is strongly recommended (and in some cases required) to engage a licensed asbestos assessor to take samples safely. They know how to collect samples without releasing fibres, and they can provide a written assessment report. Do not attempt to collect samples yourself unless you have the correct PPE and training — even small disturbances can release fibres.

Step 2 – Laboratory Analysis

Samples are sent to an accredited testing laboratory (IANZ-accredited labs are the standard in NZ). Results typically come back within a few days and will confirm whether asbestos is present and what type.

Step 3 – Review the Report

If asbestos is found, the assessor's report will usually indicate the condition of the material (friable or non-friable) and recommend next steps — which may include leaving it in place, encapsulating it with paint, or removal by a licensed removalist.

What the Rules Say About Asbestos Removal and Painting

Under NZ regulations:

• Class A asbestos removal (friable or damaged asbestos) must be carried out by a licensed Class A asbestos removalist.
• Class B asbestos removal (non-friable, bonded asbestos such as intact fibrolite sheets) must be carried out by a licensed Class B asbestos removalist if the area exceeds 10 m².
• Homeowners doing their own work on their own home are in a grey area — but WorkSafe's guidance is clear that disturbing asbestos without proper controls is dangerous regardless of who does it. Always check current WorkSafe NZ guidance before proceeding.

If the asbestos-containing roof is in good condition and not friable, a licensed roof painter may be able to apply a suitable encapsulating paint system over it — but sanding or abrading the surface is not acceptable and must not be done. Any painter working on a suspected asbestos roof should have asbestos awareness training.

Safe Steps Before Any Roof Painting Work

1. Establish the age and material of your roof before booking any tradesperson.
2. Arrange testing if there is any doubt about the material.
3. Share the test results with your roof painter before work begins — a reputable painter will ask for this.
4. Do not pressure-wash, sand, or scrape a suspected asbestos roof.
5. If removal is needed, engage a licensed asbestos removalist — you can find qualified local professionals on tradedirectory.co.nz.

When to Call a Professional

You should always call a licensed professional if:

• Your roof is fibrous cement and was installed before 1994.
• Testing confirms asbestos is present.
• The roofing material is damaged, crumbling, or friable in any way.
• The area requiring work exceeds 10 m².
• You are unsure about any aspect of the identification or testing process.

A qualified roof painter with asbestos awareness training, or a licensed asbestos assessor, can guide you through the process safely. Find experienced local roof painters and asbestos professionals on tradedirectory.co.nz.

Safety note: Never sand, grind, cut, or pressure-wash a roof you suspect contains asbestos. Even brief exposure to asbestos fibres carries long-term health risks. When in doubt, stop work and seek professional advice immediately.

Sources & Further Reading

• WorkSafe NZ – Asbestos
• MBIE Building Performance – NZ Building Code
• BRANZ – Building Research
• Standards NZ
• Licensed Building Practitioners