I bought a dehumidifier for basement after realizing RHT was at 83% down there. It is now at a comfortable 55%. I did noticed some mold on the joists but haven’t had a water problem for years. My question is: Would this dehumifier prevent the mold from getting worse or growing new mold? Keep in mind its behind the baseboard molding. Does the dehumidifier actually dry the air behind the baseboard and walls?
Moisture comes from two places. Water moves through concrete from wet to dry areas. Moisture infiltrates the home from outside into the basement via air movement. The dehumidifier removes the moisture from the infiltrating air. Most experts recommend <50%RH but 55%RH maybe OK depending on the surface temperature of the concrete. Moisture that moves through the concrete makes a wet spot and mold will grow in the wet area. A dehumidifier will reduce the area of the wet spot but not eliminate it. Mold spores will not grow and active mold goes dormat when exposed to <50%RH. Experts suggest removing any mold growth in a home. It may or may not cause illness. Suggest you monitor the isolated areas of your basement to assure humidity control. Check epa's web site for capacity and efficiency. Most small residential dehumidifiers are not efficient or have enough capacity to maintain <50% during cool extreme conditions.
