Q: My environmental company has a client that has noticed mold growth on the exterior of their building, and are wondering how it can be cleaned. It is an EIFS (Exterior Insulation and Finish Systems) building. Do you have any recommendations on a proper cleaning method?

A: The process used for cleaning the moldy surfaces you mention varies depending on the materials involved. If the EIFS that you reference is a vinyl-siding cladding system, then cleaning it should not be a problem. You can use water pressure and a simple detergent cleaner (with surfactants). Certainly you'll want to test the mixture's cleaning ability first in a non-obvious location, but vinyl-siding systems are usually easily cleanable. One caution is to make sure that the cleaning process doesn't force water into the seams and joints that are supposed to be sealed.

After cleaning this type of system, you should review the integrity of all caulking to make sure it's in good condition. This is probably the weakest component of the vinyl siding EIFS, and is the one usually pointed to when a problem occurs.

If your EIFS is other than the vinyl-siding cladding system, I'd suggest you talk to a vendor involved in providing coatings, applications and waterproofing for commercial buildings. These specialty contractors have experience in seeing the kinds of siding failures that can occur with EIFS. They can also offer some great guidance on cleaning and coating the siding to prevent moisture problems, including mold.

Travis West is the president of Building Air Quality Inc., a Houston-based indoor air quality consulting firm. He can be reached at twest@baq1.com, or toll-free at 866-367-1177. )

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