How to Install Insulation Under the Floor
- 1). Install wood lath strips every 12 inches. Nail or staple the ends of the wood lath to the joists of the floor above, creating a bridge between the joists. These will hold the fiberglass insulation in place between the joists.
- 2). Insert the fiberglass insulation into the space between the joists. Place the insulation so that the vapor barrier is facing away from you and toward the subfloor of the floor above. Feed it so that it is above the wood lath strips, which hold the insulation in place. Do not compress the insulation when installing it; this diminishes its effectiveness. If plumbing or electrical wiring is present between the joists, place the insulation on the underside of them; do not crush or compress the insulation to place it above plumbing or electrical wiring.
- 3). Insulate water pipes that are not enclosed in the underfloor insulation to R3 or higher if you live in an area with severe winters. Wrap prefabricated pipe insulation securely around any water pipes from their source to the point that they enter the insulation under the floor. Secure with duct tape or the method recommended by the manufacturer of the pipe insulation.
