Is It Safe to Use an Angle Grinder on Asbestos Cement Sheets Outdoors?

No, it is not safe — and in New Zealand it is almost certainly illegal. Using an angle grinder on asbestos cement sheets generates enormous quantities of fine asbestos dust, even outdoors. That dust contains respirable asbestos fibres that cause serious, life-threatening diseases including mesothelioma, asbestosis, and lung cancer. There is no safe level of asbestos fibre exposure, and being outside does not meaningfully reduce the risk to you, your family, or your neighbours.

Why an Angle Grinder Is One of the Worst Tools to Use

Angle grinders are high-speed, high-energy tools. When used on asbestos cement (AC) sheet — commonly found on pre-2000 NZ homes as roofing, wall cladding, eaves linings, and soffits — they pulverise the material and release millions of microscopic fibres into the air. Unlike cutting with a hand saw (which is itself still restricted work), grinding creates a sustained, invisible aerosol of fibres that can travel significant distances on even a light breeze.

Key hazards include:

• Airborne fibre spread to neighbours, passers-by, and anyone nearby
• Contamination of clothing, hair, and skin, spreading fibres indoors
• No practical way for a homeowner to achieve the dust control required by law
• Long latency period — asbestos-related diseases can take 20–40 years to appear, so there are no immediate warning signs

What NZ Law Actually Says

In New Zealand, work involving asbestos is tightly regulated under the Health and Safety at Work (Asbestos) Regulations 2016, administered by WorkSafe NZ. The key points for homeowners are:

• Class A asbestos removal (which includes most friable or high-risk work, and any work likely to disturb more than a minor amount of asbestos) must be carried out by a WorkSafe-licensed Class A removalist.
• Class B asbestos removal (non-friable material, limited quantities) must be carried out by a WorkSafe-licensed Class B removalist — or in some very limited circumstances by a competent person following strict controls.
• Grinding, cutting with power tools, or any method that is likely to make asbestos friable (crumbly, releasing fibres) is treated as high-risk work and generally requires a Class A licence.
• Even if you own the home, you are not exempt from these requirements when the work creates a risk to others.

Using an angle grinder on AC sheet would almost certainly constitute unlicensed Class A asbestos removal. Penalties under the Health and Safety at Work Act 2015 can be severe.

What About Small Repairs or Cutting?

Even for minor work — drilling a single hole or trimming a small piece — the safest and legally clearest approach is to engage a licensed asbestos removalist or assessor. If you are unsure whether your cladding or roofing contains asbestos, have it sampled and tested by a licensed asbestos assessor before touching it. Material installed before 2000 should be treated as potentially containing asbestos until proven otherwise.

BRANZ provides useful guidance on identifying common asbestos-containing materials in NZ homes.

Identifying Asbestos Cement Sheet

Asbestos cement sheet was widely used in NZ from the 1940s through to the late 1980s (and some products into the 1990s). Common locations include:

• Roofing (corrugated AC sheet)
• Exterior wall cladding (flat or textured sheets, sometimes called "fibrolite")
• Eaves, soffits, and fascias
• Internal wet-area linings in older bathrooms and laundries

You cannot identify asbestos by sight alone. Only laboratory analysis of a sample — collected by a trained person using correct PPE and procedures — can confirm its presence.

What a Licensed Removalist Will Do Instead

A licensed asbestos removalist will:

• Prepare an asbestos removal control plan
• Use wet methods and hand tools where possible to minimise fibre release
• Set up containment and decontamination procedures
• Wear appropriate respiratory protective equipment (RPE) and disposable coveralls
• Dispose of waste at an approved facility in sealed, labelled bags
• Provide a clearance certificate from a licensed asbestos assessor after the work

This protects you, your family, and your neighbours — and gives you documented proof the work was done correctly, which matters if you ever sell the property.

Building Consent Considerations

Removing or replacing asbestos cement cladding or roofing may also require a building consent, depending on the scope of work. Some replacements may qualify as exempt work under Schedule 1 of the Building Act 2004, but you should confirm this with your local council before starting. MBIE Building Performance has guidance on consent requirements.

When to Call a Professional

Call a WorkSafe-licensed asbestos removalist any time you need to:

• Remove, cut, drill, or disturb asbestos cement sheets
• Repair damaged or deteriorating AC roofing or cladding
• Renovate or demolish a pre-2000 building

Call a licensed asbestos assessor if you need material tested or a clearance certificate issued.

You can find qualified, licensed asbestos removal specialists in your area on tradedirectory.co.nz.

Safety note: If you have already used a grinder or power tool on what you suspect is asbestos cement, stop work immediately, keep others away from the area, and contact WorkSafe NZ or a licensed asbestos assessor for advice on decontamination and next steps.

Sources & Further Reading

• WorkSafe NZ – Asbestos — regulations, licensing, and guidance for asbestos work in NZ
• BRANZ — identifying asbestos-containing materials in NZ homes
• MBIE Building Performance — building consent requirements and the NZ Building Code
• Standards NZ — relevant NZ standards for asbestos management
• WorkSafe NZ – Health and Safety at Work (Asbestos) Regulations 2016 — full regulatory framework