DIY How to Insulate a Crawl Space & Duct Work

A house that sits on top of an uninsulated crawl space often has cold floors and unpleasant drafts, even if the rest of the house is well-insulated. When cold winter air can get into the crawl space underneath your house, it seeps in through the floors, and the cold floors make the entire house uncomfortable. There are several methods for insulating crawl spaces and duct work that make a house more comfortable and efficient.

Rigid foam insulation board, 2 inches thick
Expanding foam insulation
Duct tape
Batt insulation
Staple gun

Instructions

- 1
  Cut pieces of 2-inch-thick rigid foam panels to fit into the spaces between the floor joists along the outside wall of the crawl space. Press these panels into place so their outside faces are against the inside face of the interior wall.
- 2
  Fill in gaps around the edges of the rigid foam panels by applying expanding foam insulation to the gaps.
- 3
  Insulate ducts within the crawl space by cutting sheets of 2-inch-thick rigid foam insulation to fit the four sides of the ducts. Wrap duct tape around the panels to secure them to the face of the duct work. This will help keep air from the furnace warm as it passes through the cool environment of the crawl space.
- 4
  Isolate the crawl space from the living area above by putting batt insulation into the bays between the floor joists. Use paper-faced batt insulation with the paper on the bottom, and staple the paper to the underside of the joists.

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