Excess moisture, introduced by way of unsealed, vented crawlspaces, contributes to wood rot, mold growth and increased pest activity. Moisture in crawlspaces often migrates to the upper levels of the home through a “stack effect.” In essence, whatever air is below the house is also in the house. As warm air rises and escapes through the upper levels of the home, new air finds its way into the home to replace what’s been lost. Intake air comes in at the lower levels – through unsealed crawlspaces. This may lead to costly problems such as cupping of hardwood floors, mold growth, increased air conditioner loads, and swelling of millwork/cabinetry. Air infiltration from the crawlspace often carries odors and may contribute to poor indoor air quality and uncomfortable humidity levels.
Excess moisture in crawlspaces has also been associated with contributing to increased energy consumption. Wintertime ventilation cools the crawlspace contributing to heat loss from the home. In the summer, introducing warm outside air under the home contributes to heat gains, increasing cooling loads. Ventilation of a crawlspace to control relative humidity only works consistently in an arid climate. In most climates, ventilation can actually add significant quantities of moisture during humid times.
It is important to note the areas of concern when taking steps to responsibly convert your vented crawlspace to a sealed and conditioned space. Those include, but are not limited to: assuring proper water drainage, installing vapor barriers, consideration for combustion and carbon monoxide and sealing outside vents and controlling moisture with a crawlspace dehumidifier.