Under-floor mold
How Crawl Space Mold Gets Into Your Floor Framing in Crownpoint
Most crawl space mold isn't from a flood. In warm months, foundation vents pull in muggy outside air, and when it hits the cooler underside of the house, it condenses right onto the framing. Floor joists, subfloor sheathing, sill plates and rim joists stay damp for months, and the growth spreads across the wood grain in white, gray or black patches.
Exposed dirt makes it worse. Without a sound vapor barrier, the soil breathes moisture into the space all day, and any standing water after rain pushes humidity even higher. Batts between the joists absorb that dampness and droop, while cold supply ducts sweat and drip onto the insulation and the dirt.
Here's the part homeowners in Crownpoint don't expect: the stack effect pulls crawl space air up into the living area as warm air leaves through the attic. That's why a stale smell in first-floor bedrooms so often leads back to the crawl.