How To Insulate Encapsulated Crawl Space. Crawl space encapsulation requires a different insulation approach. When you're using fiberglass batting insulation material, run it about 6 inches or so onto the crawl space floor.
The water vapor barrier completely. A crawl space encapsulation’s purpose is to insulate the crawl space to prevent heat loss and to keep moisture out. Foamboard or insulation vapor barrier is the preferred choice of crawl space ninja.
Add a thermal barrier to the crawlspace walls.
Before the crawl space can be encapsulated, the area will need to be cleared out before the work can begin. To make that happen, we seal off crawlspace vents using foam board and spray foam. Sealing vents to the exterior. Cover the walls with insulation from the sill plate to the plastic covered dirt floor.