At some point, most restoration contractors have used an antimicrobial coating or sealant on the job after the water damage clean up or mold remediation is complete. However, not all understand what antimicrobial coating or sealants are, how to properly use them and their functions. While our industry has acquired a better understanding in recent years in how these products can serve as useful and complementary tools, it is critical to all that restoration professionals reduce indiscriminate use, while encouraging proper application.

Antimicrobial coatings and sealants must contain an “active ingredient,” which is a natural substance that has been tested and registered by the U.S. Environmental Protection Agency (EPA). Any registered active ingredient is certified to help prevent future mold growth on surfaces that were previously affected but have been properly cleaned and dried. It is critical that these coatings and sealants not be used before the proper removal of mold contamination (through use of disinfectants not addressed here), or in place of regular cleaning and moisture control.

The ANSI/IICRC S520–2008 is a good starting point for a summary regarding the role of coatings in restoration and remediation jobs. It is a source against which manufacturer’s claims can be evaluated. In the “Standard and Reference Guide for Professional Mold Remediation 2008” portion (Chapter 5: Tools and Materials, pg. 120-121), contractors and consultants can review information concerning coating definitions, evaluating product efficacy, product classes and use limitations.* A key section of the S520 is the clarification of the product classes for coatings and sealants. Two classes are defined:

  • Mold-Resistant Coatings: Contain EPA–registered antimicrobials for the purpose of inhibiting mold growth on or in the coating film. It is important to note that these products do not make kill claims when it comes to microbial activity, nor are they impairing future resistance into the surface material when they are applied. If a coating were to make any of these claims, the product would have to be registered with the EPA, as well as registered in any state in which the product might be sold or used.  Since these mold-resistant coatings do not make these claims, these products do not require EPA registration.
  • Fungicidal Coatings: These are coatings that deliver antimicrobial activity at the time of application. In other words, after pre-cleaning (and sometimes disinfecting or sanitizing), a fungicidal coating will kill residual mold on those surfaces. Once fungicidal coatings or sealants have cured, they continue to serve long-term as mold-resistant coatings, inhibiting future growth on or in the coating film. Because these fungicidal coating and sealants make an antimicrobial claim, these products must be registered with the EPA, as well as with any state in which they are sold or used.


Regardless of which class a coating or sealant may be in, none should be used as encapsulants or sealers over active mold. They are intended to be applied to the surface after it is properly cleaned, disinfected and dried when appropriate. Failure to properly clean and remove the mold from the surface can permit continued growth under the coating. Further, proper source-removal is one of the overarching principles of remediation which all restoration professionals must address. This fundamental step is widely endorsed by the leading authorities in the industry, including in both IICRC S520 and the New York City Guidelines (2008).

When choosing the right antimicrobial coatings and sealants, restoration and remediation professionals should ensure they are choosing products with the following characteristics:

  • Does not create a vapor barrier. Doing so could lead to unwanted build-up of moisture, and possibly contribute to future mold growth or other structural problems.
  • Demonstrates reasonable permeability as tested under ASTM International. Contractors and/or consultants can and should ask manufacturers to provide testing from an independent and certified laboratory against an ASTM test method specifically assessing permeability of coatings (ASTM D 1653).
  • Are low-odor, water-based, and contain low VOCs (volatile organic compounds).


In closing, restoration and remediation contractors using EPA-registered antimicrobial coatings or sealants find success when using these products properly. And all gain credibility and repeat/pass-along business by following best practices. Those are literally the final layer in helping to build trust and recognition for the industry. Good word-of-mouth has always been the best can’t-be-bought marketing tool and it is more critical than ever in the age of social media. Giving a customer the ability to say “it never came back” – that you prevented future incursions of mold in every area you restored – essentially seals the deal for future work. 

* This is not the final authority on coatings, but the material presented is useful for training and for asking manufacturers the right questions regarding what their products can and cannot accomplish.