In many cases, yes — asbestos cement roofing that is intact, well-bonded, and undamaged can be safely left in place. The key principle is that asbestos fibres only become a health hazard when they are released into the air, which happens when the material is friable (crumbling, broken, or disturbed). However, "leaving it alone" still requires ongoing monitoring, some legal awareness, and a clear plan for the future.
Why Asbestos Cement Roofing Was So Common in NZ
From the 1940s through to the mid-1980s, asbestos cement (AC) sheeting — often called fibrolite or Super Six corrugated roofing — was widely used across New Zealand homes, farm buildings, garages, and commercial properties. It was cheap, durable, and fire-resistant. The asbestos fibres in these products are tightly bound within a cement matrix, which is why intact AC roofing is considered non-friable and lower risk than loose or sprayed asbestos insulation.
What Makes It Dangerous
The danger arises when asbestos cement is:
- Broken, cracked, or weathered to the point where fibres can be released
- Drilled, cut, sanded, or pressure-washed — all of which generate hazardous dust
- Moss-covered and treated with harsh chemicals that degrade the cement binder
- Disturbed during re-roofing, renovation, or demolition work
Inhaled asbestos fibres can cause serious diseases including mesothelioma, asbestosis, and lung cancer — conditions that may not appear for decades after exposure. WorkSafe NZ provides detailed guidance on asbestos health risks and legal duties for managing asbestos in workplaces and homes.
The "Leave It Alone" Principle — With Conditions
If your AC roofing is in genuinely good condition, the safest short-term option is often to leave it undisturbed. Here's what that means in practice:
- Inspect it regularly (at least once a year) for cracking, spalling, moss growth, or physical damage
- Do not walk on it, drill it, or pressure-wash it
- Keep gutters clear so water doesn't back up and erode the sheeting
- If moss appears, use a low-pressure spray with an appropriate biocide — never a high-pressure washer — and check with a specialist first
- Document its condition with dated photographs — useful if you sell the property or need to manage it later
NZ Legal Requirements You Should Know
Under New Zealand law, asbestos management is governed by the Health and Safety at Work (Asbestos) Regulations 2016. While these regulations primarily target workplaces, they set the standard of care that applies broadly. Key points:
- Class A asbestos removal (friable asbestos or non-friable asbestos over 10 m²) must be carried out by a licensed asbestos removalist
- Class B removal (non-friable asbestos, such as intact AC sheeting, under 10 m²) can be done by a competent person following safe work practices, but a licensed removalist is still strongly recommended
- If you are selling, renovating, or demolishing, you may need an asbestos survey carried out before work begins
- MBIE Building Performance can advise on building consent requirements when roofing is being replaced
Always confirm your specific obligations with your local council and a licensed asbestos professional, as requirements can vary depending on the scope of work.
When You Should Act — Don't Wait
Leaving AC roofing alone is only appropriate while it remains in good condition. You should take action promptly if:
- Sheets are cracked, broken, or visibly deteriorating
- The roof has been damaged by a falling branch, hail, or other impact
- You are planning any renovation, re-roofing, or demolition
- A building inspector or asbestos assessor identifies the material as degraded
- You are selling the property and a pre-purchase inspection flags it
In these situations, do not attempt DIY removal. Contact a licensed asbestos removalist to assess and safely manage the work. You can find qualified local specialists on tradedirectory.co.nz.
Encapsulation as an Alternative
If your AC roofing is showing early signs of weathering but is not yet severely damaged, encapsulation (applying a sealant coating over the surface) can be a cost-effective option to extend its safe life. This must be done carefully by someone experienced with asbestos materials — the application process itself must not disturb or abrade the sheeting. Ask a licensed asbestos professional whether encapsulation is suitable for your roof.
Disposal: It's Not Kerbside Rubbish
When AC roofing is eventually removed, it cannot go in your general skip or kerbside bin. Asbestos waste must be:
- Double-bagged or wrapped in heavy-duty polythene and clearly labelled
- Taken to an approved disposal facility — contact your local council or regional authority to find the nearest site
- Transported in accordance with NZ hazardous waste rules
Your licensed removalist will handle this as part of the job.
When to Call a Professional
Call a licensed asbestos removalist or assessor if you are unsure whether your roofing contains asbestos, if the material is damaged, or if any work is planned that could disturb it. For removal of more than 10 m² of non-friable asbestos (or any friable asbestos), a Class A licensed removalist is legally required. Don't risk your health or the health of your family — asbestos-related diseases are irreversible. Find a qualified specialist through tradedirectory.co.nz.
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