What Proper Mould Remediation Looks Like (and What Isn't Remediation at All)
By Lisa Waayer — Naturopath, Building Biologist & Low Tox Coach | ANTA & ASBB member
Short on energy? Here's the essence: Not everything sold as "mould remediation" is remediation. Proper remediation follows the AS-IICRC S520 standard: the moisture source is fixed, affected materials are removed under containment, and fine particles and settled dust are cleaned up – and there are skilled remediators who do exactly that. But the title "remediator" isn't regulated in Australia, so the same word can cover S520-trained professionals, handyman-style clean-ups and quick fixes. The label on the invoice tells you less than the method does. Knowing what good work involves helps you ask the right questions before the works, and make sense of how you feel afterwards.
The finish line that wasn't
Here's the heartbreaking version of this story, and I hear it often: a household discovers mould, does what they're told is the right thing, pays for "remediation" – and the sensitive member of the household walks back in and reacts within days. Cue confusion, a contractor insisting the job was done, and a family with no idea whether to trust the paperwork or the person.
During my own water-damaged-building illness, I navigated this world from the client side: foggy, unwell, and trying to evaluate claims from insurers and contractors. I know exactly how disempowering it is. What follows is the plain-language version of what I learned then and what my building biology training confirms now.
One thing first, because it matters: good remediation exists, and good remediators are worth every dollar. If your work was done properly and you're feeling well, that's exactly the outcome it's designed for. This post isn't about casting doubt on good work. It's about helping you recognise it, and understand what's happened if something that was called remediation didn't deliver.
Is mould remediation regulated in Australia?
Not as a trade in its own right. There's no licence or mandatory qualification required to call yourself a mould remediator in Australia. The recognised benchmark is AS-IICRC S520, the Standards Australia adoption of the IICRC's professional mould remediation standard – but, like most Australian Standards, following it is voluntary unless a contract or law requires it.
In practice, that means the word "remediation" covers a very wide range of work. At one end are IICRC-trained remediators who work to S520, and they do this properly. Then there are operators who know the standard but cut corners, handyman-style services who've added mould to their list, and contractors working to a brief that's shaped by an insurance claim rather than by a sensitive person living in the home. All of them may use the same word or even mention the IICRC on their quote or in advertising.
Quality remediators are usually trained and certified through the IICRC – look for the Applied Microbial Remediation Technician (AMRT) certification – and are happy to show proof that it's current. It's worth asking for, and then checking that the method in the quote actually matches S520, because a logo on a website doesn't tell you how the job will be done.
So in this post, when I say proper remediation, I mean work done to S520. Anything else I'll call a clean-up or a quick fix, whatever the paperwork calls it.
What does proper mould remediation involve?
Proper remediation under S520 comes down to four things: finding and fixing the moisture source, containing the work area so contamination isn't spread, physically removing mould-affected porous materials rather than treating them, and thoroughly cleaning fine particles and settled dust – with the result confirmed at the end.
Moisture first. If the water problem that caused the growth isn't resolved, the certificate is dated the day the problem starts returning. A remediator doing the right thing will want to know where the water came from, and that it's been fixed.
Containment is where jobs quietly fail. Disturbing mould-affected materials without proper containment and air management doesn't remove a problem – it relocates a portion of it into your soft furnishings, contents, ducting and dust. A visually spotless post-works house can carry a higher fine-particle burden than before the work was started. This single failure explains a large share of the "we remediated and she got worse" stories in my sessions with patients.
Removal, not treatment. Mould growing into porous materials such as carpet, underlay, plasterboard and insulation can't be sprayed, fogged, painted or dried back to safety. Proper remediation removes those materials under containment and replaces them. Remember – mould doesn't have to be seen or smelt to be present; it can be growing hidden within materials and wall cavities.
Detailed cleaning. The fine particles that sensitised people react to settle into dust and onto contents. Thorough cleaning of non-porous materials and contents, including HEPA vacuuming and damp wiping, is part of the job, not an optional extra.
Confirmation. Good remediation ends with the result being checked, not just the work being finished. It's worth asking upfront how completion will be confirmed and by whom – checks done by someone with no stake in the invoice give you the most confidence. Ideally, that's a different party from the one who did the work.
Which common mould "fixes" aren't remediation?
Spraying or painting over mould, fogging, steam cleaning carpets, and drying out porous materials that have been wet for more than 48 hours all look like action, but none of them remove the problem. Used as the main fix, none of them is proper remediation.
Bleach, sprays and paint. Surface treatments don't reach growth within porous materials and don't address the moisture source. Painting over mould hides it, and hiding it isn't the same as removing it. Bleach only lightens its appearance.
Fogging. Fogging fills a room with a fine mist of biocide or "mould-killing" product. It can't reach into wall cavities, carpet backing or plasterboard, where much of the growth lives. And even where it does reach, killing mould isn't the goal – dead mould still leaves behind spore fragments, mycotoxins and other particles that sensitised people react to, and they stay put until they're physically removed. Fogging can also add a chemical exposure for someone who's already reactive. At best it's an add-on after proper removal and cleaning, never a substitute for it.
Steam cleaning carpets. It sounds thorough, but steam cleaning pushes hot moisture deep into carpet backing and underlay – exactly the conditions mould thrives in – and in an already damp home it often doesn't dry fully. It can't reach contamination in the underlay or subfloor, and it can stir particles into the air. Water-damaged carpet generally needs to come out, underlay and all.
Drying out long-wet porous materials. Carpet, underlay, plasterboard and other porous materials that have been wet for more than 48 hours should be assumed to have mould growing in them. Drying them at that point stops the water, but it doesn't undo the growth already in the material, which is why "we dried it out" isn't the same as "we fixed it". Fast drying within the first 24–48 hours is a legitimate part of water damage response; after that window, removal is the fix.
If one of these was your fix, you haven't done anything wrong. These methods are widely offered and they sound reasonable. Knowing the difference simply helps make sense of symptoms that didn't settle, and points to the next useful step.
Why do mould remediation quotes vary so much?
Because they're often not quotes for the same job. A fogging or spray treatment might cost a few hundred dollars. Proper remediation – fixing the moisture source, containment, removing and replacing affected materials, detailed cleaning and a completion check – takes more time, labour, equipment and disposal, so it costs considerably more. The cheapest quote can become the most expensive one if the problem returns and you end up paying twice.
I see this often: a household gets several very different quotes, and the thorough one starts to look like the outlier – even the one to be suspicious of. But when a job is priced far lower, it's usually because steps have been left out. The quick fix can feel like progress, and then the mould – and the symptoms – are back within months, with the full job still to do.
Compare scope, not just price. Ask each company to list in writing what's included: how the moisture source will be addressed, what containment they'll use, which materials will be removed and replaced, how contents will be cleaned, and how completion will be confirmed. Laid side by side, the price difference usually explains itself. A higher price isn't a guarantee on its own, though – the method still needs to match S520.
If the full job isn't affordable right now, you're not alone – it's a real constraint for many households. A good remediator or assessor can help you prioritise, and there are ways to reduce exposure in the meantime. What's worth avoiding is spending limited money on a quick fix that leaves the problem in place.
What should I ask before, during and after mould works?
Before: ask whether the work follows AS-IICRC S520, whether the remediator is IICRC-trained, and how the moisture source will be fixed. During: the sensitised person stays out of the house. After: know how completion will be confirmed, then return gradually and watch how the body responds. And throughout, support the person as well as the house.
None of this is about distrusting remediators. It's about walking in as an informed client, which good remediators welcome:
Before engaging: ask whether the work follows AS-IICRC S520 and whether the person doing it holds IICRC mould remediation training. Confirm the moisture source will be diagnosed and fixed, not just the growth removed. Ask what containment will be used, what will be removed versus cleaned, what happens to contents and ducting, and – in writing – how completion will be confirmed and by whom. If fogging, steam cleaning or "drying out" long-wet materials is the main plan, that's worth questioning before you sign.
During: the sensitised person stays out of the house during works. No exceptions worth making.
Before final payment and reoccupation: make sure the completion check you agreed on has happened. Then a staged return, watching the body's response as the final instrument.
Throughout – the clinical side: remediation ends the exposure; it doesn't rebuild the person. Naturopathic support can begin before the works, carry the person through the upheaval of works and moving back in, and continue into recovery – gentle, sequenced and matched to their capacity. That's how the household actually gets its finish line.
Where I sit in this process
I don't do remediation, and that's deliberate – it's a specialist trade with its own training and certification, and keeping it separate means my assessment has no invoice riding on the answer. Where I'm most useful is before the works and alongside the person: a building biology assessment so you understand the moisture source and likely scope before quotes arrive, help making sense of what a quote does and doesn't include, and naturopathic support for the affected person the whole way through – before, during and after the works.
And when a body keeps reacting to a home that's supposedly been fixed, a consultation that looks at the person and the history of the home together is often where the next step becomes clear.
If you're weighing up remediation quotes – or wondering whether the work you've already had done was the real thing – book a consultation before the next dollar moves. An hour of independent eyes at the right moment can save households thousands, and spare the person at the centre of it another false finish line.
Frequently Asked Questions
Is mould remediation regulated in Australia?
Not as a trade in its own right. There's no licence or mandatory qualification required to call yourself a mould remediator. The recognised benchmark is AS-IICRC S520, the Standards Australia adoption of the IICRC's professional mould remediation standard, but following it is voluntary unless a contract or law requires it. Asking whether a remediator is IICRC-trained and works to S520 is a sensible first filter.
Why did I react to my house even after mould remediation?
Common reasons: the moisture source wasn't fixed, containment was inadequate and fine particles spread into contents and dust, settled dust wasn't thoroughly cleaned, or the work was a quicker fix, such as spraying, fogging, steam cleaning or drying out long-wet materials, rather than proper remediation. A sensitised person can also react to levels others don't notice. Each of these is identifiable and addressable.
Does fogging kill mould?
Fogging may kill some mould on non-porous surfaces the mist reaches, but it can't reach growth inside wall cavities, carpet backing or plasterboard, and it doesn't remove anything. Dead mould still leaves spore fragments, mycotoxins and other particles that sensitised people react to, and fogging can add a chemical exposure of its own. It is not a substitute for removal and cleaning.
Is it safe to steam clean mouldy or water-damaged carpet?
No. Steam cleaning pushes hot moisture into carpet backing and underlay, the conditions mould thrives in, and often doesn't dry fully. It can't reach (and in fact can cause or add to) contamination in the underlay or subfloor. Carpet and underlay that have been wet for more than 48 hours generally need to be removed, not cleaned or dried.
Do you provide remediation services?
No, by design. I provide independent building biology assessment before works, help understanding what proper remediation should involve, and naturopathic support for the person throughout. My only stake is the household's outcome.