The air under your floor is your air
As warm air rises out of the top of a house, it is replaced by air pulled in from below. In many homes a large share of first-floor air passes through the crawlspace first — carrying its moisture, smell and mold spores with it.
Vents don’t dry it out
Foundation vents were meant to let the crawlspace dry. In a Hudson Valley summer they do the opposite: warm, humid outdoor air hits cool crawlspace surfaces and condenses, soaking the wood and insulation.
The ground is a moisture source too
Bare soil releases water vapor all year. A thin, torn plastic sheet is better than nothing, but it doesn’t stop it.
What fixes it
Seal the vents, cover the floor and walls with a sealed heavy-duty liner, insulate the foundation walls, and run a dehumidifier. If water collects, add drainage and a sump pump first.
We can help: Crawlspace encapsulation — Seal out ground moisture, insulate the walls and turn a damp crawlspace into a clean, dry one.