No — pressure washing an asbestos cement fence yourself is not safe and is strongly discouraged in New Zealand. High-pressure water breaks down the cement matrix and releases asbestos fibres into the air, where they can be inhaled by you, your family, and your neighbours. Even a fence in apparently good condition can shed fibres when disturbed. Here is what you need to know before you pick up that pressure washer.
Why Asbestos Cement Fences Are Dangerous When Disturbed
Asbestos cement (sometimes called fibrous cement or, in older NZ homes, "Super Six" or "Hardiflex" style corrugated sheeting) was widely used in New Zealand fencing and cladding until the mid-1980s. The asbestos fibres are bound into the cement and are relatively stable when the material is intact and undisturbed — this is called non-friable asbestos.
The problem is that pressure washing:
- Physically erodes the cement surface, exposing and releasing fibres
- Creates a fine aerosol mist that carries fibres deep into the lungs
- Contaminates surrounding soil, garden beds, and stormwater
- Can spread fibres to neighbouring properties
Once inhaled, asbestos fibres can cause mesothelioma, asbestosis, and lung cancer — diseases that may not appear for 20–40 years after exposure. There is no safe level of exposure.
What NZ Law Says
In New Zealand, work involving asbestos is regulated under the Health and Safety at Work (Asbestos) Regulations 2016, administered by WorkSafe NZ. Key points for homeowners:
- Class A asbestos removal (friable asbestos or any removal over 10 m²) must be carried out by a licensed asbestos removalist.
- Class B asbestos removal (non-friable asbestos under 10 m²) can be done by a competent person following strict controls, but pressure washing is never an acceptable method regardless of area.
- Homeowners working on their own homes are not automatically exempt — if the work creates a risk to others (neighbours, passers-by), WorkSafe's regulations still apply.
- Disposing of asbestos waste is also regulated; it must go to an approved facility, not your kerbside bin.
Check with your local council about any additional regional requirements before starting any asbestos-related work.
What You Can Safely Do Yourself
If your asbestos cement fence is in good condition (no cracks, crumbling, or visible deterioration), the safest approach is to leave it alone. Encapsulation — painting over it with a suitable sealant — can extend its life without disturbing fibres.
If you want to clean the surface gently, you may:
- Wipe it down carefully with a damp cloth (not a hose or pressure washer)
- Apply a penetrating sealant or encapsulant paint — products designed for this purpose are available from paint specialists; Resene and Dulux can advise on suitable exterior sealants
- Wear P2-rated disposable gloves and a P2 respirator (not a dust mask) if you touch the surface at all
- Wet the surface lightly with a hand sprayer before any contact to suppress dust
- Double-bag any cloths or materials used and dispose of them as asbestos waste
Never sand, grind, drill, cut, or pressure wash asbestos cement. These are all high-risk activities that release fibres.
Identifying Whether Your Fence Contains Asbestos
If your fence was built before 1990, there is a reasonable chance it contains asbestos. You cannot tell by looking at it. The only reliable way to confirm is to have a sample tested by an accredited laboratory. An asbestos assessor or removalist can take a sample safely. BRANZ provides guidance on identifying asbestos-containing materials in older NZ homes.
Removal or Replacement
If the fence is deteriorating, cracked, or you want it removed, hire a licensed asbestos removalist. They will:
- Assess whether Class A or Class B removal applies
- Set up containment and use appropriate PPE
- Wet the material during removal to suppress fibres
- Dispose of waste at an approved facility with the correct documentation
- Provide you with a clearance certificate
Replacement fencing using modern fibre cement (which does not contain asbestos) from manufacturers such as James Hardie is a popular and durable option once the old material is safely removed.
When to Call a Professional
Call a licensed asbestos removalist if:
- Your fence is crumbling, cracked, or weathered
- You need to remove any panels (even a small number)
- You are unsure whether the material contains asbestos
- Any renovation or building work will disturb the fence
- You have already pressure washed it (seek advice on decontamination)
You can find qualified, licensed asbestos removal specialists in your area on tradedirectory.co.nz. Always ask to see their WorkSafe licence before work begins.
Safety Note
If you believe you have already disturbed asbestos cement — through pressure washing or other means — leave the area, keep others away, and contact a licensed asbestos assessor promptly. Do not attempt to clean up the residue yourself.
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