Q:How can we prevent molds from appearing on a painted exterior veneer ceiling?

A: I assume that the location of the exterior ceiling is such that it gets little direct sunlight and may even be in a moist (high humidity or rain) environment.  Not knowing what the construction of the substrate or surface of the exterior ceiling, there are a couple of considerations that can be looked at.  First of all, the construction of the ceiling should be made out of a material that is not susceptible to water damage or mold growth, such as cement board materials (hardi-plank) or non wood/cellulose materials.  The other consideration is the type of primer and paint used on the ceiling.  Both the primer and the paint should be of a mold-inhibitor type.  There are manufacturer’s of paint that sell these types of products and they can work fairly effectively to prevent or minimize mold growth on surfaces.  The last consideration is to clean the ceiling surfaces on a regular basis with a mild soap/bleach solution.  If dirt is kept from the surfaces, then the mold growth is also minimized.  Any or all of these steps can help to minimize mold growth on the exterior painted ceiling.

Rick Anderson, P.E., Manager, EFI Global, Inc. Houston Office.

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