IICRC S520: The Mould Remediation Standard Explained

When you hire a mould remediator, how do you know they’re doing the job properly? The answer lies in the IICRC S520 — the gold standard for mould remediation in Australia and worldwide. Understanding this standard helps you evaluate whether the company you’re hiring follows best practices, and protects you from substandard work that leaves your mould problem unresolved.

What Is the IICRC S520?

The IICRC S520 is the “Standard for Professional Mould Remediation” published by the Institute of Inspection, Cleaning and Restoration Certification. First released in 2003 and updated in 2015, it establishes procedural standards for the assessment, containment, removal, and verification of mould contamination in residential and commercial buildings. It is the most widely recognised mould remediation standard in the restoration industry, referenced by insurers, regulators, and health authorities.

When you engage certified mould removal services, IICRC certification ensures the work follows scientifically validated protocols rather than ad hoc methods.

Key Requirements of the Standard

The S520 mandates specific procedures at every stage of remediation:

• Assessment: Comprehensive moisture mapping and mould identification before work begins
• Documentation: Written remediation plan, pre-work documentation, and progress records
• Containment: Physical isolation of work areas using barriers, negative pressure, and HEPA filtration
• Personal Protection: Appropriate PPE for workers based on contamination level
• Source Removal: Physical removal of contaminated porous materials rather than encapsulation
• Antimicrobial Treatment: Use of registered antimicrobial products on remaining surfaces
• Verification: Post-remediation clearance testing to confirm successful decontamination

Contamination Levels

The S520 classifies mould contamination into three conditions based on the extent and nature of growth, each requiring progressively more rigorous remediation protocols. Condition 1 is normal fungal ecology (acceptable background levels). Condition 2 is settled spores on surfaces that may not yet show visible growth. Condition 3 is active mould growth with visible colonisation. Most residential remediation involves Condition 3 situations, requiring the highest level of protocol.

A mould inspection determines which condition applies to your home and informs the appropriate response level.

Why IICRC Certification Matters

Hiring a non-certified mould remediator is a gamble. Without S520 training, companies may skip containment (spreading spores throughout your home), use ineffective cleaning methods, fail to identify hidden mould, neglect moisture source remediation, or skip post-remediation verification. These shortcuts save the company time and money but leave you with a partially resolved problem that will return.

mould risk assessment to understand your situation, and always verify that any remediator you hire holds current IICRC certification.

What to Ask Your Remediator

Before hiring, ask: Are you IICRC certified? Do you follow the S520 standard? Will you provide a written remediation plan? What containment measures will you use? Do you conduct post-remediation verification testing? Will I receive a clearance report? A reputable company will answer all these questions confidently and provide documentation to support their claims.

For more on what to expect from professional removal and what the process looks like in practice, our detailed walkthrough explains each stage of professional remediation. Understanding the process — and the mould inspection costs — empowers you to make informed decisions about protecting your home.