Key takeaways
- Vented crawl spaces are insulated at the floor
- Sealed crawl spaces are insulated at the walls
- Fiberglass can sag and hold moisture
- Rigid foam and spray foam resist moisture
The right place for insulation depends on how the space is built and managed.
Vented space
Insulation goes between the joists to keep the floor warm, and ducts and pipes sit in the cold. Batts can sag and absorb moisture if the space stays damp.
Sealed space
Insulation goes on the walls and rim joist, which brings the space inside the thermal boundary. Pipes and ducts stay in a milder environment.
Choosing
If the space is damp, fix that first. Then pick the approach that suits your climate and plan.
Related services
Questions about your own crawl space? Call or text 800-224-9245, or use the quote form below.