Excessive moisture can cause structural damage and can reduce indoor air quality. In the summer, if warm and humid outdoor air is allowed to enter basements and crawl spaces, it will condense on the cooler inside surfaces. This can occur when foundation windows and vents are left open when outdoor temperatures are above approximately 60º. The result ranges from a musty smell at minimum to serious mold and mildew problems to, at worst, wet and rotting building components.

A wet basement can cause moisture problems throughout the house. Make sure that there is a full perimeter drainage system on the interior or exterior of the foundation. As long as a proper drainage system is installed and any dirt floors are covered and sealed with heavy plastic, there's no need for venting basements or crawl spaces in Vermont.

Look for signs of flooding such as white stains on the inside of foundation walls. Roof gutters and proper landscape grading will ensure that groundwater and rain move away from the house. Downspouts from gutters should be clean and should extend out and 10 feet away from the foundation. A curtain drain installed a distance from the house will reroute water from an uphill slope and direct it away from the foundation.

Air leakage into basements and crawl spaces during warm weather can be the cause of large amounts of moisture entry to your home. During cold weather, air leakage can be the reason for excessively dry air in your living spaces. To find air leakage locations in basements and crawl spaces, look for moving cobwebs and daylight on the interior of the foundation, especially where the wood sills sit on the foundation and also around windows and doors. A professional Home Performance with ENERGY STAR® energy auditor can use a "blower door" to identify and quantify air leakage areas in your home. Click here to learn more about Home Performance with ENERGY STAR and find a contractor near you.