S520 Standard
The IICRC's ANSI-accredited standard for professional mold remediation. Defines inspection and assessment procedures, containment categories, remediation methods, personal protective equipment, and post-remediation verification for mold-contaminated buildings.
The IICRC S520 Standard for Professional Mold Remediation defines the professional baseline for assessing, containing, and remediating mold contamination in structures. It is referenced throughout the mold remediation industry and by most insurance carriers handling mold losses.
Assessment Before Remediation
S520 emphasizes that remediation follows assessment. Before any mold removal begins, an assessment identifies the extent of contamination, the moisture source driving mold growth, and the affected materials. Fixing the moisture source is critical because mold will return if the underlying water problem is not resolved.
Containment Categories
S520 defines levels of containment based on the size and nature of the contamination. Smaller limited contamination may require source containment with poly sheeting and a HEPA-filtered air scrubber. Larger contamination triggers more rigorous containment with negative air pressure, full enclosure, decontamination chambers, and upgraded PPE. Technicians working inside contained areas use respirators and protective clothing appropriate to the containment level.
Remediation and Verification
Remediation under S520 includes physical removal of mold-contaminated materials, HEPA vacuuming and wet wiping of non-porous surfaces, and antimicrobial treatment where appropriate. Post-remediation verification confirms the work is complete, typically through visual inspection and sometimes through air or surface sampling by an independent assessor. Many carriers and building occupants require documented clearance before reoccupancy.
Frequently asked questions
S520 covers the inspection, assessment, containment, and remediation of mold-contaminated structures. It defines categories of containment based on the affected area, required PPE for technicians, remediation procedures, and post-remediation verification standards.
S520 recommends post-remediation verification, which may include visual inspection and/or clearance sampling depending on the project scope. Many jurisdictions and carriers require third-party clearance testing before remediated areas can be reoccupied or rebuilt.
Yes. S520 focuses specifically on mold contamination, which requires containment, HEPA filtration, PPE, antimicrobial treatment, and careful handling to prevent spore dispersal. Water damage under S500 is focused on drying, which is a different operational challenge even though water and mold are often related.
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