Building Science: Moisture Trapped in Your Home

Moisture always moves from areas of higher concentration to areas of lower concentration. This rule explains why it is so important to put plastic sheeting under indoor concrete slabs and why we coat foundation walls.

Moisture is known to move from wet areas to drier areas, making it very important, especially with concrete, to keep things dry. The plastic vapor barrier stops the movement of water from the soil, where there’s a high moisture concentration, to the home’s interior, which has a lower concentration.

Sometimes people think that their wet crawlspace or basement is not an issue because they don’t use the space, even for storage, Unfortunately, the water that seeps into wet basements and crawlspaces does not stay there. It moves through the house by wicking, evaporation, and convection.

The solutions for wet basements vary, but stopping the water intrusion or directing it to a sump pump should be a top priority. Sealing as many holes as possible that connect the basement or crawlspace to the rest of the house is important, too.

Plugging the holes closes air leaks, which carry water vapor into the living space. Sometimes people try to dry their basement or crawlspace by opening the windows. This might help during periods of very low humidity, but it also can make things worse because outside air often contains more water vapor than cooler basement air.

Keeping your home dry and free from excess water is important to prevent buildups of unseen molds and bacterias. Excess moisture in a home can be dangerous for health, especially in young children, so it is very important to take control over a dangerous situation.

For more information on building sciences, visit Fine Homebuilding