For a homeowner to know how to properly insulate a crawlspace, they must understand some of the bad insulation practices in a crawlspace. Some homes have fiberglass insulation in between the floor joists and some homes do not. The reason a crawlspace has fiberglass insulation is because the vents are open in the winter causing pipes to freeze and cold floors. The problem with fiberglass insulation is that is considered mold candy, and works best in a closed cavity and not in a ventilated crawlspace
For years, standard building practices was to insulate the floor with fiberglass insulation over a ventilated, unconditioned crawlspace. According to the U.S. Department of Energy, a better approach is to build a well sealed, unventilated crawlspace (i.e., encapsulation system) by sealing and insulating the foundation walls with polystyrene insulation(foam board) rather than the sub-floor.
Insulating a Sealed Crawlspace
A sealed crawlspace is the best solution to preventing cold floors, high energy bills, and frozen water pipes. Sealing the crawlspace with our AmeriBrite Encapsulation System alone can make your home more energy efficient by up to 18%. Adding rigid foam board insulation behind or in front of the liner will also add to the overall energy efficiency benefits.
Encapsulating your crawl space is the first step. If sealing is not enough, then adding crawl space insulation is the next step. The cost of crawl space insulation pays for itself with its energy efficient benefits.
According the energy efficiency and renewable energy guide for crawlspace insulation, the advantages of crawlspace insulation in a unventilated, sealed crawl are as follows:
- You can avoid the problems associated with a ventilated crawlspace (IE mold, dry rot, etc..)
- Less insulation is required (around 400 square feet for a 1,000-square-foot crawl space with 3-foot walls.)
- Piping and duct work are within the conditioned volume of the house so they don’t require insulation for energy efficiency or protection against freezing.
- Air sealing between the house and the crawl space is less critical.