Is my fibre cement board asbestos? Hardiflex, Hardiplank and older sheet in NZ

What is the difference between fibre cement and asbestos cement?

Only the fibre. Both are thin, hard sheets of cement and sand, reinforced with fibre so they can be made thin and nailed up. In asbestos cement, the reinforcing fibre is asbestos. In modern fibre cement it is treated cellulose, which is wood fibre. Finished and painted, the two are close to identical: the same grey core, the same weight, the same sound when you knock on them.

That is why so many searches ask "fibre cement or asbestos?". The honest answer is that age is the strongest clue and a laboratory is the only proof.

When did James Hardie stop using asbestos in New Zealand?

For Fibrolite, the sheet most New Zealand houses of the 1950s to 1970s were clad, lined or soffited with, the date is September 1983. Nigel Isaacs, writing in Architectural History Aotearoa in 2021, records that James Hardie had made Fibrolite asbestos-cement at its Penrose plant since 1938, and that from September 1983 a treated cellulose fibre replaced the asbestos.

James Hardie's own asbestos fact sheet gives the company-wide dates: in 1981 it made the world's first asbestos-free fibre cement products, it ceased using asbestos in its building products in 1985 and in its pipes in 1987, and its products have been asbestos-free since. The two accounts fit together: the switch happened product by product through the first half of the 1980s.

What is Hardiflex?

Hardiflex (now sold as Hardie™ Flex) is James Hardie's flat, unsanded fibre-cement sheet: cement, sand and cellulose fibre, not wood and not plasterboard. In New Zealand it is sold in 6mm sheets for cladding extensions, gable ends, porches and carports, and in 4.5mm sheets for eaves and soffits. James Hardie gives it a 15-year product warranty.

Prices are Bunnings NZ's online prices for special-order sheets and vary by store; Mitre 10 lists the same sizes but asks you to call your local store for a price. Eaves lining also comes in narrower 450, 600 and 750mm widths for soffits. None of these new sheets contains asbestos. The question is only ever about old sheet already on a house.

When did Hardiflex stop containing asbestos?

By 1985 at the latest. James Hardie says it stopped using asbestos in all its building products in 1985, and its New Zealand Fibrolite sheet switched to cellulose fibre in September 1983 (Isaacs, 2021). So a Hardie sheet made after 1985 is asbestos-free. A flat sheet put up before then, whatever it is called, may be asbestos cement and needs a test before anyone cuts it.

The catch is that you rarely know when a sheet was made. Old flat sheet is often called "Hardiflex" or "Fibrolite" by habit, the way plasterboard gets called GIB. If the house or the soffits are older than the mid-1980s and nobody has reclad them, assume the sheet is original.

Does Hardiflex or Hardiplank contain asbestos?

Hardiflex, Hardiplank or any other Hardie product bought new today does not. James Hardie says its products have been asbestos-free since it stopped using asbestos in the 1980s. The question that matters is when your sheet was made, and the name alone won't tell you that. A sheet stamped with a brand on the back, sitting in a house built in 1979, is a different question from the same name on a 2015 extension.

• Built or reclad after about 2000, with the original sheet: low risk, and WorkSafe says so for buildings from 1 January 2000.
• Built in the late 1980s or 1990s: most new local fibre cement was asbestos-free by then, but older stock and imported sheet were still around. Not cleared by date alone.
• Built before 1984, or any sheet of unknown age: treat it as possibly asbestos until a test says otherwise.

Can you tell asbestos from fibre cement by looking at it?

Not reliably, and nobody honest will tell you otherwise from a photo. Some clues narrow it down: the building's age and its consent file, an old invoice, a date or brand printed on the back of a sheet you can see from the roof space, or a sheet that is obviously newer than the rest. None of them is proof. Snapping a corner off to look at the broken edge is exactly the disturbance that releases fibres if it is asbestos, so don't.

Modern fibre cement has its own dust hazard: cutting or grinding any cement sheet makes respirable crystalline silica dust, which is why the manufacturers' safety data sheets focus on cutting methods. "Asbestos-free" doesn't mean "dust-free".

What should you do before cutting or removing old fibre cement?

1. Work out the age of the sheet as best you can: the house's build date, any recladding, and whether the sheet in question matches the rest.
2. If there's any chance it went up before 2000 and you are about to cut, drill, sand, water-blast or remove it, get one sample tested. One $249 test covers a visit and one sample; extra samples at the same visit are $85. Asbestos testing cost in NZ compares that with other providers and DIY kits.
3. If it is positive, the amount decides who may remove it. Over 10 m² of non-friable asbestos needs a Class B licence: see the rules.
4. If your work touches several materials around the house, a refurbishment survey is better value than testing one sheet at a time.

For where fibre cement shows up around a house — soffits, cladding, wet-area linings — see asbestos cement cladding and soffits. For roofs, see asbestos roofs and Super Six.