A crawl space floods from below or from above: groundwater and storm runoff through the foundation walls and vents, or a supply pipe, drain or water heater leaking through the floor. Either way the water pools on the vapor barrier, soaks the fiberglass between the joists and raises the humidity of the whole house.
What gets removed and what gets dried
- Standing water pumped off the vapor barrier
- Fiberglass insulation that sagged or soaked, bagged and removed
- A torn or contaminated vapor barrier pulled out
- Joists, sill plates and subfloor dried in place with air movers and a dehumidifier
Why crawl spaces dry slowly
The space is tight, cool and damp to begin with, so the drying team usually closes the vents and works it as a sealed drying chamber with a dehumidifier. Readings on the joists and subfloor, not the feel of the air, decide when the equipment leaves.
Frozen pipes and crawl spaces
Supply pipes that run through a crawl space are among the first to freeze in a January cold snap, and a split there can run for hours before anyone notices. The Ready.gov winter weather page covers pipe protection, and EPA indoor air guidance explains why damp air under the house matters upstairs.
When the cold is the cause, see frozen pipe water damage.
