The first thing to do, would be to try to determine if there is a leak or other source for the moisture. Consider what type of heat you have, Have you changed the type of heat you have? Could it be causing condensation in or on the walls or under the floor? Have you recently started using a clothes dryer in your home? Is it vented properly to the outside? There are many things to consider when moisture problems arise. BUT you must find the source and stop it before you can do any repairs. If it's a humidity problem with no apparent source, a dehumidifier may be all you need.
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