 on cooler surfaces such as ductwork) drop below the dew point, creating a damp environment that is hospitable to indoor mold growth as well as infestations by rodents and insects, possibly including wood-damaging ones such as termites or carpenter ants.Even without condensation, relative humidity above 80% can support mold growth and rot wooden structural materials such as floor joists.Humidity in some sealed crawl spaces is controlled using a dehumidifier.