Subfloor & Crawl Space Mould Removal in Sydney

Musty smell inside? Damp, stained or mouldy timber under the house? AAA Mould Removal finds where the moisture is coming from, removes the mould from the subfloor framing, dries the timbers and makes sure the work is checked independently.

Quick answer: subfloor mould grows when the space under a raised timber floor stays damp, usually from a plumbing or shower leak, rising damp from the soil, or poor ventilation. Removing it means fixing the moisture source, cleaning or removing the mould from the bearers, joists and flooring, drying the timbers, and having the result checked by an independent assessor. Recent subfloor jobs cost $4,500 + GST for a 2-day make-safe and $8,000 + GST for a 5-day remediation with structural drying. The inspection and quote are free.

IICRC Certified Firm, certified in water damage (WRT), mould remediation (AMRT) and structural drying (ASD)
Indoor Environmental Professional (IEP), Testing Water-Damaged Buildings
NSW licensed builder (392154C) for timber and flooring replacement
Free subfloor inspection with moisture meters and thermal imaging

Why Mould Grows Under the House

The subfloor is dark, closed in and rarely visited, so moisture there can go unnoticed for months. The causes we find most often:

Plumbing leaks: a slow leak from a water or hot water pipe dripping into the subfloor
Failed shower waterproofing: every shower sends a little more water through to the timbers below
Rising damp: water from the soil and around the footings keeps the crawl space humid
Poor ventilation: blocked or too few vents, garden beds against the walls, or a low crawl space

Signs to look for: a musty smell inside, mould or water stains on the bearers and joists, damp soil under the house, a higher water bill, or soft or cupped floorboards.

A subfloor fan helps keep the space dry, but it won't fix a leak or remove mould that is already there.

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How We Remove Subfloor Mould

1. Free inspection: We go under the house and map the mould and the wet areas with moisture meters, thermal imaging and humidity readings. Where needed, we smoke-test to see whether subfloor air is reaching the rooms above.

2. Fix the source: The leak, drainage or ventilation problem has to be fixed first, or the mould comes back. We tell you who you need and check the source is fixed before we start.

3. Protect: Our team works in full PPE (full-face respirators, disposable coveralls, gloves) and we stop contamination being carried into the house.

4. Remove: We clean the mould off the bearers, joists and flooring by HEPA vacuuming, sanding or scraping, then HEPA vacuum again. Timber that is too damaged is cut out and replaced by our NSW licensed builder (392154C).

5. Dry: Structural drying brings the framing back to a dry standard so it can't support new growth.

6. Encapsulate if needed: If a bathroom rebuild or other work is coming, we can clean and encapsulate the surfaces as a temporary make-safe until the builder starts.

7. Check and clear: We run our own quality check first, including in-house mould microscopy. Then an independent assessor does the post-remediation verification. We don't sign off our own work.

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Subfloor Mould Removal Cost

Every subfloor is different. The price depends on how much framing is affected, how wet it is, how much access there is, and whether timber needs replacing. As a guide from recent jobs:

Make-safe under a bathroom, surface growth cleaned and encapsulated (Hazelbrook): 2 days, $4,500 + GST
Remediation and structural drying after a hot water pipe leak (Matraville): 5 days, $8,000 + GST
Professional mould and moisture report, if you need one for insurance or a landlord: from $500 + GST

These are examples only, not a quote.

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Recent Subfloor Mould Jobs in Sydney

Real subfloor jobs from Michael Nguyen and the team, with photos of each step:

Matraville hot water pipe leak: a slow leak under a brick veneer home on piers. Inspection, remediation and structural drying in 5 days for $8,000 + GST, with independent clearance.
Hazelbrook shower leak make-safe: failed shower waterproofing. Surface growth cleaned and encapsulated in 2 days for $4,500 + GST, ready for the bathroom rebuild.
Wollstonecraft subfloor remediation: a failed bathroom membrane leaking into the subfloor, and the PPE our team wears for the work.
Burwood smoke test: how musty subfloor air was getting into the house through gaps in the floor.
Leichhardt rising damp: widespread mould on the joists, with humidity of 80 to 100% under the house.

Click HERE for a FREE Mould Inspection Today!

Subfloor Mould FAQs

Straight answers to the questions we get asked most

Is mould under the house a problem?

Yes. Subfloor air moves up into the rooms through gaps in the floor, and damp timber keeps decaying. A musty smell inside is often the first sign. Our inspection is free.

Can I just spray the mould?

Spraying doesn't fix the moisture that caused it, so the mould grows back. The source has to be fixed, the mould physically removed from the timber and the subfloor dried.

Do I need a plumber first?

If you know there is a leak, get it fixed first. If you are not sure where the moisture is coming from, book an inspection: we'll find the source and tell you who you need.

Landlords, Strata & Real Estate

Musty smells and subfloor mould are a common tenancy and strata complaint. We give landlords, property managers and strata committees a clear answer on the cause (a leak, rising damp or poor ventilation), fix it properly and document the work with photos and, if needed, a professional report.