Mold-resistant coatings, encapsulants and other shortcuts

In plain English

Fungicidal and mold-resistant coatings are paints or sealers with a bound antimicrobial. R520 says they are meant to discourage future growth on surfaces that have already been properly cleaned and dried, especially where moisture is hard to control. They are not a way to cover live growth. Mold under the film can keep growing if the material behind it stays damp, and dirt left on the surface stops the product from working.

R520 says coatings belong after post-remediation verification, because they can interfere with it. Where there is concern that an opaque product might hide uncleaned mold, a clear coating allows later inspection. Coatings can also change how a material breathes, which can trap moisture, and how it burns. R520 also dismisses UV light as impractical for mold remediation and treats heat and other new treatments as developing methods to be judged against the core principles.

Sometimes growth cannot reasonably be removed, or a moisture source cannot be fixed. In that case R520 allows a deviation: managing the area in place with long-term controls or encapsulants. It strongly discourages this. The customer should be told in writing that it may work poorly, release contaminants, need ongoing management and lead to more work later, and that follow-up assessment may be needed.

“Fungicidal coatings should not be used as sealants or encapsulants to contain or cover active, viable mold growth.”

Key points

• Coatings go on clean, dry, verified surfaces only.
• Never paint or seal over active mold growth.
• A clear coating lets later inspectors see what is underneath.
• UV light is not a practical remediation method.
• Leaving growth in place is a documented exception, not a method.

Official text

This topic is covered in our own words because the standard behind it is copyrighted; we cite it below rather than reproduce it.

Citations

• IICRC S520 Reference Guide, IICRC S520 Standard and Reference Guide for Professional Mold Remediation — Reference Guide — Ch. 5, p. 64. Best practice
• IICRC S520 Reference Guide, IICRC S520 Standard and Reference Guide for Professional Mold Remediation — Reference Guide — Ch. 5, pp. 67–69. Best practice
• IICRC S520 Reference Guide, IICRC S520 Standard and Reference Guide for Professional Mold Remediation — Reference Guide — Ch. 11, pp. 122–124. Best practice
• IICRC S520 Reference Guide, IICRC S520 Standard and Reference Guide for Professional Mold Remediation — Reference Guide — Ch. 13, p. 140. Best practice

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