Existing cellulose · the honest answer
Is your existing cellulose insulation safe?
If you’ve been told your existing cellulose might contain asbestos, be a fire risk, or that you should rip it out, take a breath. Cellulose is recycled paper fibre and borate. It never contained asbestos. Correctly treated, it resists flame. And nothing should be torn out of your roof on a hunch, only on a test result.
I’m Peter Johnson. After 40 years in roofs all over South East Queensland, I’ve seen plenty of homeowners frightened into a needless rip-out by an insurer or a rival installer. Here’s the straight story: what cellulose is, what it isn’t, and how to settle it for certain.
Recycled paper + borate
asbestos-free by composition
Straight up
Cellulose never contained asbestos. They’re not even the same kind of material.
Let me put this plainly, because it’s the one that scares people most. Modern cellulose insulation is recycled paper fibre, around 75–85% by weight, treated with borate. Asbestos is a mineral dug out of the ground. Cellulose is plant and paper fibre. One is a rock fibre, the other is shredded newspaper. It is asbestos-free by composition. There’s no version of cellulose that ever had asbestos in it.
So where does the fear come from? From two completely different loose-fill products that genuinely did contain asbestos, and because they were also poured loose into roofs, people muddle them up with cellulose:
“Mr Fluffy” loose-fill asbestos
Raw loose-fill amphibole asbestos pumped into ceilings in parts of the ACT and NSW from about 1968 to the early 1980s. This is the genuinely dangerous one, and it’s the subject of a government buy-back and removal programme. See the NSW Government loose-fill asbestos page and the Australian Government asbestos product guide.
Asbestos-contaminated vermiculite (Zonolite)
A pebbly mineral granule that, from some mines, was contaminated with asbestos. The US EPA has detailed guidance on asbestos-contaminated vermiculite insulation. It looks like little gold-to-grey flakes, nothing like paper.
I’ve written a full side-by-side on this (how to be sure which product you’ve actually got) on Mr Fluffy asbestos vs cellulose. And if you’ve found something unexpected in your roof, our asbestos-in-my-roof answer walks you through what to do next.
This is cellulose: grey, shredded paper fibre laid as one soft blanket. If this is what’s in your roof, it’s asbestos-free by composition, recycled paper and borate, nothing more.
Tell them apart
Three loose-fill products, three very different looks.
The quickest way to calm a worry is to look at what's actually up there. These three get confused, but side by side, they couldn't be more different.
Cellulose: safe
Grey, shredded paper and lint. Soft and fluffy, like the inside of an egg carton. Recycled paper treated with borate. Asbestos-free by composition. This is the good stuff, the kind we make and pump.
Mr Fluffy: dangerous
Raw, fibrous loose asbestos. Often a greyish-blue or brownish loose fibre, poured straight in. Installed ACT/NSW ~1968–early 1980s. Do not disturb it. This is the one the government buy-back exists for.
Vermiculite: test it
Pebbly gold-to-grey flakes. Looks like little puffed mineral chips, not paper. Some (such as Zonolite) was contaminated with asbestos at the mine. If you’ve got this, get it tested before anyone touches it.
The honest bottom line: if it’s grey shredded paper, it’s cellulose and it’s asbestos-free by composition. If you genuinely can’t tell, or it looks like raw fibre or pebbly flakes, don’t poke at it. Leave it undisturbed and get a lab to identify it. Certainty is cheap; panic is expensive.
Fire-retardant, not fireproof
Borate makes cellulose resist flame. The real fire risk is something else.
People hear “paper insulation” and picture a fire hazard. It’s the opposite. The paper fibre is treated with borate. Boric acid suppresses smouldering, borax suppresses flame spread. Sustainability Victoria’s housing manual puts it plainly: “the treatment ensures that, if the material does ignite, the flame will not spread.” CSIRO’s thermal-insulation guidance describes borate-treated cellulose the same way.
In Australia, the early-fire-hazard behaviour of a building material is measured by the AS/NZS 1530.3 test. I’ll be straight with you on the language: correctly borate-treated cellulose is fire-retardant, it resists flame spread, and it’s smoulder-resistant, but I’ll never call it “fireproof”, because nothing in a roof is.
Where the real fire risk lives
- Untreated or under-treated material. If the borate isn’t there in the right amount, the fire protection isn’t either. The treatment is the whole point.
- Any insulation packed against old downlights. Old recessed halogen downlights run hot. Any insulation jammed hard against them with no clearance is a risk — cellulose, batts, anything. The fix is clearance or a fire-rated fitting, not blaming the insulation.
So when correctly borate-treated cellulose is installed properly, with clearance kept around hot fittings, it isn’t the fire risk. Bad workmanship is.
The real reason people call
If your old cellulose “isn’t working”, it’s almost always the install, not the product.
Here’s what actually happens nine times out of ten. Someone rings worried their cellulose is a problem, the room’s still hot, the insulation “isn’t doing anything”. Almost every time, the product’s fine. It was just installed badly the first time, very often in a house they’ve bought, where a previous owner had it done during the 2009–10 insulation grant by a contractor who wasn’t trained well enough to know how much to put in.
The common one is under-filling. They didn’t pump in the depth and density that was paid for, so it never performed. That isn’t the cellulose settling or failing; it’s a job that was short-changed from day one (more on that on does cellulose settle?). The fix is usually simple: I come back and top up or correct what was done before, to the right settled density, and you finally get what you should have had the first time. I’d say 9 in 10 of these calls end with a straightforward top-up, not a removal.
Get it installed correctly (the right depth, the right density) and none of this happens. That’s the whole reason we train every Comfort Zone franchise installer to install it properly. The product was never the issue. Bad workmanship was.
“Sometimes it’s the opposite of under-filling. I know of one grant-era job where they packed the entire roof void so full of cellulose that the sheer weight tore the ceiling down. That’s not the product failing. That’s an installer who had no idea how much to put in.”
Too little and it doesn’t work; far too much and it’s a load the ceiling was never built for. The right amount, installed by someone trained to measure it, is the whole game.
“You should remove it”
Removal should be driven by a test result, not the word “loose-fill”.
When an insurer or an installer tells you to rip out your insulation, ask one question: based on what? A test, or a fault you can point to, or just the fact that it's loose-fill?
- 1
“Loose-fill” is not a reason on its own
Lots of perfectly safe products are loose-fill, cellulose among them. The word describes how it goes in, not what it's made of. A blanket 'rip out all loose-fill' line lumps safe cellulose in with the genuinely dangerous Mr Fluffy product, and that's not fair to you or your wallet.
- 2
If it's modern cellulose, it's asbestos-free by composition
You don't remove a roof full of recycled paper and borate because of an asbestos worry. There's no asbestos in it to begin with. That's a firm fact about what the material is, not a promise about a particular batch.
- 3
If anyone's unsure, test, don't rip out
A NATA-accredited lab test on a small sample costs roughly $40–140 per sample and settles the question for certain. That's a tiny fraction of removing and replacing a whole roof's insulation. Let the result decide.
- 4
Watch who's giving the advice
An installer who doesn't sell cellulose has a commercial reason to tell you to rip it out and put their product in. That doesn't make them wrong, but it does mean the advice should rest on a test or a documented fault, not on talking down a competitor's product.
My honest message hasn’t changed in 40 years: test, don’t panic; test, don’t rip out. A documented fault, a leak, vermin, fire damage, is a real reason to act. A vague worry or a sales pitch isn’t. If you want a second set of eyes before you commit to anything, that’s exactly what I’m here for, including telling you to leave it alone if that’s the right answer.
The genuinely dangerous one
What “Mr Fluffy” actually is, so you know it isn’t your cellulose.
This ABC News explainer covers the real loose-fill asbestos product. Worth a watch. Once you've seen what it is, the difference from grey paper cellulose is obvious.
Mr Fluffy was raw loose-fill amphibole asbestos, a real and serious problem with its own government removal programme. It is not cellulose, which is recycled paper and borate. Two entirely different materials that share nothing but the word “loose-fill”.
Honest answers
Questions I get about existing insulation.
Does cellulose insulation contain asbestos?+
No. Modern cellulose insulation is recycled paper fibre (around 75–85% by weight) treated with borate. It never contained asbestos. Asbestos is a mineral fibre dug out of the ground; cellulose is plant and paper fibre. They aren't the same family of material at all. The confusion comes from two completely different loose-fill products: 'Mr Fluffy' loose-fill amphibole asbestos, installed in parts of the ACT and NSW from about 1968 to the early 1980s (per the NSW Government), and asbestos-contaminated vermiculite such as Zonolite (per the US EPA). If you've got grey shredded paper fibre, that's cellulose. It's asbestos-free by composition.
How do I tell cellulose apart from Mr Fluffy or vermiculite?+
By eye, they look quite different. Cellulose is grey, shredded paper and lint, soft, fluffy, like the inside of an egg carton. Mr Fluffy loose-fill asbestos is raw, fibrous, often a greyish-blue or brownish loose fibre that was poured straight in. Asbestos-contaminated vermiculite (Zonolite) is a pebbly, gold-to-grey flaky granule that looks like little puffed mineral chips, not paper. If you're not sure what's in your roof, don't disturb it. A NATA-accredited lab test on a small sample settles it for certain.
Is cellulose insulation a fire risk?+
Correctly borate-treated cellulose is fire-retardant, not a fire risk. The paper fibre is treated with borate. Boric acid suppresses smouldering and borax suppresses flame spread. Sustainability Victoria's housing manual puts it plainly: the treatment ensures that, if the material does ignite, the flame will not spread. In Australia the early-fire-hazard behaviour of building materials is measured by the AS/NZS 1530.3 test. The real fire concern isn't correctly-treated, correctly-installed cellulose. It's untreated or under-treated material, or ANY insulation packed hard against old recessed downlights with no clearance. We never call it fireproof, because nothing in a roof is.
My insurer (or an installer) says I should remove my loose-fill insulation. Should I?+
Not on the word 'loose-fill' alone. Removal should be driven by a test result or a documented fault, not by the fact that the insulation is loose-fill, because plenty of safe products (including cellulose) are loose-fill. If it's modern cellulose, it's asbestos-free by composition. If anyone is genuinely unsure what's up there, a NATA lab test on a sample (roughly $40–140 per sample) settles it for a tiny fraction of what a needless rip-out costs. Worth remembering, too: an installer who doesn't sell cellulose has a commercial reason to tell you to rip it out and replace it with their product.
How much does it cost to test insulation for asbestos?+
A NATA-accredited laboratory test on a single sample is usually in the range of about $40–140 per sample. That's a small price next to the cost, and mess, of removing and replacing a whole roof's worth of insulation that turns out to have been perfectly safe all along. My honest advice is the same every time: test, don't panic; test, don't rip out. Let the lab result make the decision, not a sales pitch or a vague worry.
My cellulose doesn't seem to be working. Is the product the problem?+
Almost never. Nine times out of ten when someone calls me about cellulose 'not working', the product's fine. It was just installed badly the first time, usually by an undertrained contractor during the 2009–10 insulation grant. The common one is under-filling: they didn't pump in the depth and density that was paid for, so it underperforms. Occasionally it's the opposite. I know of one grant-era job where they packed the whole roof void so full that the weight tore the ceiling down. Neither is the cellulose failing; both are bad workmanship. The fix is usually a straightforward top-up or correction to the right settled density, and you finally get what you should have got the first time. Installed correctly (depth and density right) none of this happens, which is exactly why we train every franchise installer to do it properly.
I've got old cellulose in my roof. Is it still doing its job and is it safe to leave?+
In most cases, yes. Cellulose that was correctly borate-treated and properly installed is asbestos-free by composition and stays fire-retardant for the life of the roof. If it's intact, dry and covering the ceiling, there's usually no reason to touch it. The things actually worth checking are unrelated to the cellulose itself: insulation packed hard against old, non-fire-rated downlights, signs of a roof leak, or rodent activity. If you'd like a second opinion, I'm happy to climb up, have a proper look and tell you straight what I find, including if I find nothing wrong.
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