Mould Remediation — What to Expect

Professional mould remediation in Australia is performed to ANSI/IICRC S520:2025 — the current edition of the Standard for Professional Mould Remediation, published by the Institute of Inspection, Cleaning and Restoration Certification (IICRC). This is the professional benchmark referenced by insurers, loss adjusters, and the Australian Financial Complaints Authority (AFCA) when assessing whether mould remediation was completed appropriately.

All contractors in the NRPG network hold current IICRC Applied Microbial Remediation Technician (AMRT) certification. For the full ANSI/IICRC S520:2025 standard, visit iicrc.org.

Mould growth following water damage or flooding is not a surface problem. Mould grows into porous building materials — drywall, insulation, timber framing, and subfloor — and cannot be removed by surface cleaning alone. Disturbing mould growth without proper containment releases airborne spores throughout the property, spreading contamination to previously clean areas.

An ANSI/IICRC S520:2025-certified contractor is trained to:

• Assess the full extent of mould growth — including inside wall cavities, subfloor spaces, and ceiling insulation not visible during inspection
• Identify and control the moisture source before remediation begins — to prevent re-growth after the job is complete
• Establish physical containment to prevent cross-contamination of clean areas during remediation work
• Remove affected porous materials correctly within containment, rather than attempting surface-only cleaning that leaves mould in the substrate
• Conduct independent clearance testing after remediation to verify the property has returned to normal air quality before containment is removed
• Document all findings, work completed, and clearance results for your insurance claim

A general cleaner or handyman does not have this specialist training. Improper mould disturbance — dry brushing, blowing, or cleaning without containment — is a common cause of wider contamination in properties where mould was discovered after water damage.

An ANSI/IICRC S520:2025-certified job produces documentation that supports your insurance claim. If a contractor cannot provide these records, the job may not have been performed to standard:

• Pre-remediation assessment report — Written scope documenting all affected areas and materials, the moisture source identified, and the remediation approach for each material type.
• Containment and negative pressure records — Confirmation that physical containment was established before remediation work began, isolating affected areas from clean spaces.
• Materials removal documentation — Records of affected porous materials removed (drywall, insulation, carpet) within the containment zone.
• Clearance testing report — Independent air and surface sampling results taken after remediation, confirming the property has returned to normal air quality. This is the close-out document required before re-occupancy.
• Photographic evidence — Before and after photographs of all affected areas.

Clearance testing results are what AFCA references when a policyholder disputes whether mould remediation was completed. A job without a clearance report is not complete under ANSI/IICRC S520:2025.

Mould growth can begin on wet building materials within 24–72 hours under the right conditions. Properties that experienced flooding or water damage where structural drying was not completed to the ANSI/IICRC S500:2025 standard are at ongoing risk of secondary mould damage — often appearing weeks after the original claim was closed.

Signs that secondary mould damage may have resulted from inadequate original drying:

• Musty odour appearing weeks after drying equipment was removed
• Visible mould on walls, skirting boards, or flooring near the original water-affected area
• Soft or damp areas in walls or ceilings adjacent to the original incident
• No daily moisture reading records from the original drying contractor

Secondary mould damage caused by an insurer's contractor failing to dry adequately is a covered loss under most policies — the insurer is responsible for the quality of work performed by their preferred contractors. An independent ANSI/IICRC S520:2025 assessment documents whether the mould growth is attributable to the original incident and what remediation is required.

In 2026, the US National Defense Authorization Act (NDAA) mandated ANSI/IICRC S520 as the mould remediation standard for military housing. This federal mandate does not apply to Australian properties — Australia has its own regulatory framework — but it is a significant credibility signal for the standard itself.

When the US federal government selects a single standard to govern mould remediation across its entire housing portfolio, it reflects the rigour of that standard's methodology. The same standard — ANSI/IICRC S520:2025 — is what NRPG's certified contractor network works to on Australian properties.

Australian alignment: AS-IICRC S520:2025 is the Australian-aligned edition, maintained by Standards Australia in parallel with the IICRC publication. NRPG contractors hold IICRC certifications — the underlying standard methodology is equivalent.

Why this matters when choosing a contractor: Competitors marketing "leading" mould services without IICRC certification are not working to this standard. The method the US federal government mandated for its most demanding housing portfolio is the method a certified contractor brings to your property.

Mould remediation disputes most commonly arise when insurer-assigned contractors perform surface cleaning only — without containment, without removing affected structural materials, and without clearance testing. If you have concerns about the work performed:

1. Request all documentation — Ask for the pre-remediation scope of works, containment records, materials removal documentation, and clearance testing report before accepting the claim closure.
2. Get an independent ANSI/IICRC S520:2025 assessment — An independent certified contractor can document current mould conditions and whether the original remediation was completed to standard.
3. Lodge an internal dispute with your insurer — Attach the independent assessment and request a formal review. All Australian insurers must have an internal dispute resolution (IDR) process.
4. Escalate to AFCA — If the insurer does not resolve the dispute within 30 days, AFCA accepts complaints at no cost and can require insurers to pay for remediation of inadequate managed repairs.