Why fiberglass fails in crawl spaces
Fiberglass works by trapping dry air. Under a humid crawl space it soaks up moisture, gets heavy, and pulls away from the subfloor. Wet insulation stops insulating, holds moisture against the wood, and becomes a home for mold and pests.
The better approach: insulate the walls
When a crawl space is sealed, it becomes part of your home's conditioned envelope. Instead of insulating the floor, we insulate the foundation walls and rim joists. That keeps the whole crawl space near indoor temperature, so pipes and ducts stay protected and the floors above feel warmer in winter.
- Rigid foam board on foundation walls, sealed at the seams
- Closed-cell spray foam on rim joists, where air leaks are most common
- Removal and disposal of old, wet fiberglass
If your crawl space stays vented
Some homeowners are not ready for full encapsulation. In that case we can remove failed batts and install moisture-resistant insulation held tightly against the subfloor with proper supports. We will explain the trade-offs so you can decide.
Benefits you will notice
- Warmer floors in winter
- Less work for your heating and cooling system
- Fewer drafts from rim joist gaps
- No more insulation falling onto the ground
- A cleaner crawl space that is easier to inspect