Insulating the Crawl Space Walls or Ceiling
If there are ductwork and mechanicals present in the crawl space, we recommend laying plastic down on the ground and then spraying the crawl space walls as well as the rim joist. Doing this will seal off the foundation of your home, allowing the crawl space to be around the same temperature as the rest of the home.
An added bonus of this installation method is that the heat from the mechanicals in the crawl space will move freely through the floors, adding even more comfort.
If there are no mechanicals or ductwork present in the crawl space, crews would instead spray the crawl space ceiling to air seal the crawl space completely from the rest of the home.