I have a homeowner (who is an engineer ) who says that the temperature
differential between the inside attic and the exterior ceiling board is causing moisture
to develop, resulting in mildew and mold forming on his porch ceiling. Do you have any
suggestions to solve this problem?
John, a home builder.
A) We do NOT
recommend insulating any attic space, covered porches, garages or walls that are
not air-conditioned. Moisture on covered porch ceilings does cause mold and mildew,
however, it has nothing to do with the temperature differentials from the attic.
Most covered porches will have moisture
problems which breed mold and mildew due to the fact moisture gets on the ceilings and can
not dry out fast enough, especially during the rainy seasons.
One suggestion would be, if your homeowner has a ceiling fan on this
covered porch, keep it running during the rainy season. If he does not have one, tell him
to add one. This will help but still may not solve this problem.
Also make sure to avoid using oil base paints on any ceilings, siding
or facial boards, only use enamel latex semi-gloss or flat paint for the best results to
help prevent mold and mildew, also use a mold and mildew inhibitor added to the paint.
Using mold and mildew inhibitors will help, however, it will not last forever. After a few
years mold and mildew will return. Nothing really stops "outside" mold and
mildew from coming back and attacking our siding, facial boards, and most of all covered
Care and Maintenance is to wash the ceiling and all
infected areas once a year with a 1/3 bleach* 2/3 water mix using a pump-up-sprayer. Wear
eye protectors and keep the infected areas moist with this mixture for at least 15
minutes. (Also do a search for a product called: Wet & Forget.)
Again, most covered porches can not really dry out well enough and will
continue to support mold and mildew and that's our climate.