Under the house
Crawl spaces
Why vented crawl spaces fail on the wet coast, and what encapsulation, liners, and drying actually do.
On the wet coast, outdoor air is often as damp as the crawl. Venting can pull humid air under the house instead of drying it.
Bare soil releases moisture for months. A continuous ground cover (vapor barrier) is the first cheap step. Overlap seams, run plastic up walls, and keep it from shredding into trip hazards.
Encapsulation and mechanical drying are larger projects. They make sense after bulk water (grade, gutters, downspouts) is controlled. A dehumidifier in a still-flooded crawl is the wrong first move.
Soft rim joists, musty first-floor air, and chronically high humidity under the house are signals to inspect, not ignore.