Core drilling through an asbestos cement (AC) wall is not safe to do yourself and, in most situations, is legally restricted work in New Zealand. Drilling into asbestos-containing material (ACM) generates fine respirable fibres that are invisible to the naked eye and can cause serious, life-threatening diseases including mesothelioma and asbestosis. Before you pick up any power tool near a wall you suspect contains asbestos, read this guide carefully.
Why Asbestos Cement Is So Dangerous When Drilled
Asbestos cement — commonly found in pre-2000 NZ homes as fibrolite cladding, soffit linings, eaves boards, and internal wall linings — is considered a bonded (non-friable) material when it is in good condition. However, the moment you cut, grind, sand, or core drill it, you fracture the cement matrix and release asbestos fibres into the air. A core drill is particularly hazardous because it generates a sustained, high-speed abrasion over a large surface area, producing a significant volume of fine dust in a very short time.
Exposure to even a small number of asbestos fibres carries a cumulative health risk, and there is no known safe level of exposure recognised by health authorities.
NZ Legal Requirements for Working With Asbestos
Under the Health and Safety at Work (Asbestos) Regulations 2016, all asbestos-related work in New Zealand is classified as either Class A or Class B licensed work, or in limited cases, unlicensed work. Here is how it breaks down:
| Work Type | Description | Who Can Do It |
|---|---|---|
| Class B | Disturbing bonded ACM (e.g. drilling, cutting fibrolite) in limited quantities | Class B licensed removalist |
| Class A | Friable asbestos or larger-scale bonded ACM removal | Class A licensed removalist |
| Unlicensed | Very minor disturbance (e.g. removing a small number of non-friable AC sheets intact, no breakage) | Trained competent person with correct PPE |
Core drilling through an AC wall almost certainly falls into Class B licensed work at minimum, because it actively disturbs and damages the bonded material. A homeowner cannot legally carry out this work themselves in most circumstances. WorkSafe NZ is the authority on these regulations and their website has detailed guidance.
First Step: Confirm Whether Your Wall Contains Asbestos
If your home was built or renovated before 2000, assume any cement sheet lining or cladding may contain asbestos until proven otherwise. Do not drill a sample yourself. Instead:
- Hire a licensed asbestos assessor to take a sample safely and have it tested by an accredited laboratory.
- Check the BRANZ website for guidance on identifying common ACM locations in NZ homes.
- Review the MBIE Building Performance resources on asbestos in buildings.
Testing is relatively affordable and gives you certainty before any work begins.
What a Licensed Professional Will Do
A licensed asbestos removalist carrying out a core drill penetration through an AC wall will typically:
- Prepare an asbestos removal control plan
- Isolate and contain the work area with plastic sheeting
- Use a H-class (P3) vacuum attached to the drill to capture dust at the source
- Wear appropriate respiratory protective equipment (RPE) — at minimum a P2 half-face respirator, often a full-face P3 unit
- Wet-suppress dust where practicable
- Dispose of all waste (including drill bits and PPE) as asbestos waste at an approved facility
- Provide a clearance certificate on completion
This is not something that can be replicated safely with a standard dust mask and a shop vacuum.
Building Consent Considerations
If you are core drilling through an external AC wall to install a pipe, duct, or cable, you may also need a building consent depending on the scope of work. Penetrations associated with plumbing or drainage are restricted building work under the NZ Building Code. Always check with your local council before starting, and note that Licensed Building Practitioners must carry out or supervise restricted building work. Plumbing connections must be done by a practitioner registered with the Plumbers, Gasfitters and Drainlayers Board, and electrical connections by someone registered with the Electrical Workers Registration Board.
When to Call a Professional
You should always engage a licensed asbestos removalist before core drilling through any wall that contains or may contain asbestos cement. There are no DIY workarounds that are both legal and safe for this type of work. A qualified professional will:
- Confirm the presence of asbestos through proper testing
- Hold the correct Class A or Class B licence issued under NZ regulations
- Carry appropriate insurance
- Provide documentation for your records (important for future sale or renovation)
You can find licensed asbestos removal specialists in your area on tradedirectory.co.nz. Always ask to see their licence before work begins.
Safety Note
⚠️ If you have already drilled into a wall you suspect contains asbestos: stop work immediately, leave the area, close off the space to others, and contact a licensed asbestos assessor. Do not vacuum the dust with a standard vacuum cleaner — this will spread fibres further.
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