How to Insulate Pipes in an Unheated Crawl Space

Measure the supply pipes and add enough length to allow a thermostatic-controlled electric heating wire to reach the nearest electrical receptacle.

Place the plug from the thermostatic-controlled electric heating wire next to an electrical receptacle in the crawl space. If no receptacle is available, drill a hole that will accommodate the plug, through the floor near a hidden receptacle. Behind the refrigerator or through a cabinet are acceptable locations.

Run the heat wire straight along the side of the pipe and fasten it in place with electrical tape every 8 to 10 inches. Continue to run the heat wire and secure it in place with electrical tape until all supply pipes have a wire running along the side.

Measure the length and diameter of the pipes and match foam pipe insulation to the pipe's dimensions. Pull the foam pipe insulation apart along the precut seam and fit it over the pipe. Make cuts to the foam pipe insulation as necessary with a utility knife. Wrap duct tape over the pipe insulation every 10 to 12 inches to secure it in place.

Examine the crawl space for gaps and cracks. Clean the gaps with an all-purpose cleaner and a scrub brush. Run a bead of exterior-grade silicone sealant into the gaps to prevent cold airflow.

Put on safety goggles, gloves, protective jumpsuit and a dust mask. Place the correct R-value batt insulation between the floor joists and over pipes. Staple the insulation to the joists and sill plate with galvanized staples and a heavy-duty stapler. Allow the insulation to drape rather than fit it tightly to the crawl space ceiling. Draping reduces airflow more effectively than tightly fitting insulation with wire cages.

Measure and cut exterior-grade rigid foam board insulation to fit the walls of the crawl space with a utility knife. Attach furring strips to the masonry walls inside the crawl space every 20 to 22 inches. Drive galvanized nails through the rigid foam board insulation into the furring strips around the entire crawl space.

Plug the thermostatic-controlled electric heating wire into the electrical receptacle and set the temperature according to the manufacturer's recommendations.