In addition to moisture and mold problems, air quality must be considered in basements. After sealing gaps and cracks to mitigate moisture movement, let air exchange and ventilation systems control the air movement in the basement. A properly functioning home incorporates airtightness and good ventilation.
Because of the confined space of a basement, an air exchange system will vent out stale air and replace it with fresh air. Installing a ventilation system sized for the space is often a better choice because the system recovers heat from the exhausted air and uses it to warm the replacement air. Units can be purchased that also work as a dehumidifier, which is a plus for potentially damp basements.
An exhaust fan, such as a bathroom vent fan, can be purchased that can be set to run continuously at a desired CFM. The fan vents the stale air, which now has to be replaced with fresh air. Ports can be installed away from the exhaust fan that allow outside air to enter.
Combustion appliances, such as furnaces or boilers and hot water heaters, often use the air from inside the home for combustion. After you reduce the available air by sealing cracks and gaps, the appliance may struggle for air and the exhaust gases may have trouble exiting through the chimney—another reason to install an air-exchange system.
You also shouldn’t hide combustion appliances in a small closet or an area that has been sealed for sound control. A combustion safety test is recommended before the basement remodeling work starts and during and after work is complete. If you are replacing combustion appliances, consider sealed combustion appliance or bring in required level of air with an air exchange system. Sealed combustion appliances draw combustion air from outdoors and have a sealed exhaust system. A lot of the new heating systems are this type because they are safer, easier to install and are typically the more efficient models.
Myron Ferguson is owner of Ferguson Drywall Innovations Inc., Middle Grove, N.Y. He has 30 plus years’ experience as a drywall contractor, is a member of the National Association of Home Builders, and is an author and teacher who provides instruction about drywall and related topics.