Don't break a piece off to check
Asbestos fibres are more likely to be released when the material is crumbly, in poor condition, or disturbed by sanding, drilling, cutting or water-blasting. So don't snap off a corner, drill a test hole or water-blast the moss off for a better look. Don't walk on it either. WorkSafe lists fibrolite sheets, which usually contain asbestos, among the brittle roofs that workers shouldn't walk on.
Start with the age of the house
WorkSafe says a home built before 1 January 2000 may contain asbestos, and the risk is lower for homes built after that date. Extensions or refurbishments done before 2000 may contain it too, so a newer-looking addition on an older house still counts.
The import dates explain the long tail. Importing raw blue and brown asbestos became illegal in New Zealand from 1984, but importing products that contain asbestos only became illegal in 2016.
If you have the original plans, a builder's report or old council records, look for words like fibrolite or asbestos cement. They're clues, not proof.
Where asbestos turns up on and around a roof
- Cement roof sheets, including corrugated roofing panels such as Super Six
- Cement ridge capping along the top of the roof
- Cement spouting (gutters) and downpipes
- Flat sheets in the gables and eaves
- Fibrolite sheets anywhere on the roof or walls
What if my roof is metal or decramastic?
Longrun and corrugated iron are steel, so the roofing sheets themselves aren't asbestos cement. That doesn't clear the whole roof. Look at the spouting, the eaves and any cement-sheet sections, and remember a pre-2000 house can have asbestos in other places.
Decramastic and other pressed metal tiles are worth asking about. Whether a particular decramastic roof contains asbestos is something only a test can tell you. What we do know is that WorkSafe's cleaning guidance groups weathered asbestos cement and decramastic tile roofs together: low-pressure biocide, surface kept wet, never high-pressure spraying or blasting. If your decramastic roof is pre-2000, get it tested before anyone cleans, cuts or removes it.
How to find out for sure
Note the age and the materials
Work out when the house, and any additions, were built. Photograph the roof, spouting and eaves from the ground.
Get a sample tested
WorkSafe says the only way to confirm asbestos is a sample tested by a reputable contractor. They take the sample under controlled conditions, so nobody is breaking bits off by hand. Health NZ says a sample tested in an approved laboratory is the most certain way to know, and suggests talking to a health protection officer at your public health service before a sample is taken.
Treat it as asbestos until you know
Until the result comes back, don't let anyone cut, drill, water-blast or walk on the roof.
Tell the roofer before they quote
Anyone quoting on a cement or older decramastic roof needs to know about the test and its result. It changes who does the work and how.
If you're a landlord, plan ahead
WorkSafe says landlords must make sure work at their property is done safely, and where it could expose people to asbestos fibres, identify the asbestos and prepare an asbestos management plan.
Is it dangerous to live under?
WorkSafe says bonded asbestos in good condition that's left alone generally doesn't release fibres. The risk comes from disturbing it, or from material that's crumbling or in poor condition.
So an intact asbestos cement roof isn't an emergency. It's something to manage: keep people off it, don't let anyone water-blast it, and plan what you'll do when it reaches the end of its life.
Be careful in the ceiling space. Health NZ says the ceiling under an asbestos roof may hold high concentrations of asbestos dust, particularly if the roofing is weathered and brittle. Leave the insulation and dust up there alone until you know what the roof is.
If the test comes back positive
You have three broad options: leave it alone and keep an eye on it, have it cleaned and coated by someone who follows WorkSafe's low-pressure method, or have it removed and re-roofed. Our guide to asbestos roofing in New Zealand compares them.
Removal has firm rules. Taking off more than 10 square metres of non-friable asbestos, counted across the whole project, needs a Class B or Class A licensed removalist, and WorkSafe says a large area can't be split into smaller sections to dodge that. A whole house roof is far bigger than that limit.
If it's already been disturbed
If someone has broken, drilled or water-blasted it by accident, WorkSafe's advice is to stop, keep people and pets away, close doors and windows, wipe yourself down with damp rags and double-bag your outer clothes. Then contact an asbestos contractor or your local health protection officer.
What you can do, and what needs a professional
You can
- Work out the age of the house and any additions
- Photograph the roof, spouting and eaves from the ground
- Keep children, pets and visitors off it
- Tell any roofer or painter about it before they quote
- Try our asbestos checker for a quick read on how likely it is
Leave to a roofer
- Taking and testing a sample
- Any cleaning, which must be low pressure with no blasting
- Cutting, drilling or fixing anything to it
- Removal over 10 square metres, which needs a licensed removalist
- Anything that means being up on the roof
Our first move
If the house is pre-2000 and the roof, spouting or eaves look like cement sheet, we'd treat them as asbestos and get a sample tested before anyone quotes for cleaning, painting or a re-roof. It's a small step, and every decision after it gets easier.
Want a roofer to take a look?
Tell us the job and your postcode. We match it with a Find My Roofer certified roofer who specialises in that kind of work, and they call you to quote. Your number goes to them alone.