Plastic Sheet Over Insulation In Crawl Space

Polyethylene sheeting is measured in mils a mil is equal to 0 001 inch of thickness.

Plastic sheet over insulation in crawl space.

You may also want to install a polyurethane vapor barrier over the dirt floor for further protection. Stretch the plastic sheet tightly across the top of the wall and staple it to the studs and plates. Without such a barrier condensation can infiltrate your home s walls and insulation creating a substantial risk of mold and mildew. Plastic on the outer surface of a wall in cold weather could cause problems.

However americover recommends 10 mil or higher for crawl space applications. If water vapor diffuses or infiltrates into the wall cavity and finds the cool surface moisture problems can occur. The reason being that unfortunately simply putting vapor barrier crawl space plastic sheeting down is not enough to solve all the issues that will ever arise in your crawl space. Hammer masonry nails through 1 by 2 inch strips of pressure treated lumber to hold the top of the polyethylene in place.

Roll out and cut plastic sheets. Beginning at one side of the crawl space lay down 6 mil or thicker polyethylene plastic over the entire crawl space. This requires less insulation and will eliminate the need to insulate ducts and pipes separately. Homeowners use plastic to cover their crawl spaces to control moisture and create a barrier against vapor.

A so called termination strip made of wood holds the plastic in place. Install the plastic sheeting only after the insulation wiring and plumbing have been completed. Codes for residential applications often cite a 6 mil 0 006 inch thick minimum reinforced poly vapor barrier. The cool surface is the sheathing assuming no exterior insulation.

As an added measure you can tape the seams in the sheets together to keep the plastic in place. If your crawl space isn t ventilated insulate the walls of the crawl space rather than the subfloor of the room above. Installation is one thing but maintenance of the vapor barrier and of the crawl space in general is the other important side of the equation and it is often overlooked. Plastic sheeting can also help turn a crawl space into a usable storage area.

Americover offers thicknesses all the way up to 20 mil. Overlap the seams by no less than 12 inches and secure them together with the poly pvc tape. Plastic on the outside.