IICRC S520:2025 Mould Remediation — What It Means for Your Insurance Claim

The IICRC S520 Standard for Professional Mold Remediation is the benchmark document governing how certified restoration contractors must assess, contain, remediate, and verify the clearance of mould-affected property. The 2025 edition is the current published version.

S520 is the technical reference for mould remediation in Australia's insurance claims context. AFCA and the Insurance Council of Australia recognise S520 methodology as the industry standard for assessing whether a mould remediation scope is technically reasonable. An independent S520-compliant assessment from a certified contractor is the primary tool for challenging an inadequate insurer scope or a mould exclusion applied to a covered water damage event.

IICRC official information: iicrc.org/standards

Mould insurance claims in Australia are disputed more frequently than most other damage types. The most common insurer positions and how S520 methodology addresses each:

• "Mould is a maintenance exclusion" — most policies exclude mould arising from gradual moisture, lack of ventilation, or failure to maintain. However, mould caused by a sudden covered event (burst pipe, storm water ingress, flood) is typically covered. S520 assessment documents the specific moisture pathway from the covered event to the mould colony, establishing sudden-event causation.
• "The mould was pre-existing" — insurers may assert that mould predated the event. S520-compliant assessment examines moisture patterns, mould colony maturity, and the physical pathway of water migration to establish timeline and causation. Date-stamped moisture readings from prior to and after the event are particularly important in this context.
• "The water damage was repaired adequately" — if the insurer's contractor did not complete S500-compliant structural drying (with documented moisture readings to dry standard), residual moisture remained in the structure. S520 assessment identifies that moisture and documents the causal link to mould development, establishing that drying was incomplete.
• "The scope of mould is too large" — insurer-appointed assessors frequently minimise the area of mould growth, particularly in concealed spaces. S520 methodology requires investigation of all areas where moisture was elevated, not just visible mould surfaces.

An S520-compliant mould assessment generates documentation that covers:

• Visual inspection findings — all visible mould colonies documented with photographs, measurements, and location within the building.
• Moisture investigation — moisture readings of all affected and adjacent materials, identifying elevated moisture conditions that support ongoing mould growth or predict further development.
• Causation analysis — identification of the moisture source or pathway that generated the mould, establishing whether it is connected to a covered event or a maintenance issue.
• Affected material inventory — identification of all materials that must be removed or remediated, with technical justification for each decision.
• Remediation protocol specification — the containment, removal, treatment, and clearance testing requirements specific to the affected property.

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Clearance testing verifies that mould remediation is complete by confirming that airborne spore counts in the remediated area are at or below outdoor baseline levels. Under S520 methodology, clearance testing must be conducted:

• After remediation is completed, before containment barriers are removed.
• By a qualified independent party who did not perform the remediation — self-clearance by the remediating contractor is not consistent with S520 principles.
• With results documented against outdoor baseline measurements taken at the same time and location.

Clearance testing matters for your claim because it establishes completion. If your insurer's contractor completed remediation without clearance testing, you have no documented basis for knowing whether remediation was effective. If mould recurs after a remediation that lacked clearance testing, the insurer cannot demonstrate that the remediation met S520 requirements — which supports a supplementary or repeat-scope claim.

AFCA (Australian Financial Complaints Authority) is the free, independent dispute resolution service for insurance complaints. Mould claims are among the most frequently escalated claim types at AFCA because they involve causation disputes that are difficult to resolve at insurer level.

For a successful AFCA mould claim outcome, the following documentation is most useful:

• Independent S520-compliant assessment documenting causation, affected area, and required scope.
• Evidence of the original covered event — photographs, insurer correspondence, repair records, or BOM data for weather events.
• Prior water damage restoration documentation — drying logs, moisture readings, or absence thereof — establishing whether prior restoration met S500 methodology.
• Timeline of discovery — documented evidence of when mould was first identified, supporting that it arose from the covered event.

Lodge a mould claim AFCA dispute at afca.org.au. No cost to lodge. NRPG does not control claim outcomes — AFCA and your insurer determine final decisions.