IICRC S520
Also called: S520, ANSI/IICRC S520, mold remediation standard, IICRC mold standard, AMRT
The ANSI-approved industry standard for professional mold remediation, published by the Institute of Inspection, Cleaning and Restoration Certification. It defines contamination conditions, containment, removal, PPE and post-remediation verification. 'To S520' describes a method, not a spray.
There’s no federal mold regulation for homes, and only a handful of states license the work, so the standard the industry actually uses is a private one: ANSI/IICRC S520, the Standard for Professional Mold Remediation, with its companion reference guide. It’s what certification courses teach, what insurers expect on a claim, and what a competent remediator means when they describe their process.
Its core ideas: a home is classified by condition — Condition 1 is normal, Condition 2 has settled spores but no growth, Condition 3 has actual growth — and remediation returns Condition 3 areas to Condition 1. Growth on porous materials (drywall, insulation, carpet pad) means removal; growth on semi-porous and non-porous materials (framing, concrete, metal) means cleaning by HEPA vacuuming, damp wiping, and sometimes abrasive methods. The work happens under containment with negative air, workers wear respirators and suits, waste is bagged and sealed, and the job ends with an independent post-remediation verification. The moisture source is identified and corrected. Notably, it doesn’t call for killing mold with chemicals as the primary method — removal and cleaning are, with antimicrobials as an adjunct.
The IICRC also certifies individual technicians (Applied Microbial Remediation Technician, AMRT) and firms. Asking a remediator whether their work follows S520 and whether their technicians are AMRT-certified is a reasonable filter, and a contractor who hasn’t heard of it isn’t a remediator.