Too much moisture in a home can lead to mold, mildew, and other biological growth. This in turn can lead to a variety of health effects ranging from more common allergic reactions, to asthma attacks, and hypersensitivity pneumonitits, for example. Excess moisture can be in the form of high relative humidity including humidity generated by people and their activities such as showers, cooking, or drying clothes. Water can also come from plumbing leaks, wet boots, or splashing around sinks.
The Damage That Moisture Can Do…
Moisture can travel with infiltrating outdoor air (or exfiltrating indoor air) through the building shell, including the foundation. In addition to health problems, high relative humidity or water that enters building cavities that is not allowed to dry quickly can lead to problems such as rot, structural damage, and premature paint failure.
How You Can Control Moisture
Methods to control moisture include building an energy-efficient home with proper air-sealing, proper use of vapor barriers and vapor diffusion strategies. The entire building envelope, from the foundation to the roof, should be designed to not only prevent moisture entry, but also to allow any moisture which does enter a means to escape. As mentioned above, people and their activities in a home are big sources of moisture; thus proper ventilation is also important in order to maintain indoor humidity levels within an acceptable range.