Vapor Barriers Cost

• Vapor retarder paint costs about $20 -$40 a gallon or $60 -$90 for a five-gallon pail. For example, Sherwin Williams Master Touch Latex Vapor Barrier Primer sells for about $80 for a five-gallon pail. Vapor barrier paint is usually white and used as an undercoat primer. It varies by brand, but generally one gallon will cover about 300-400 square feet; a five-gallon pail will cover 1,500-2,000 square feet. Vapor retarder paint is not as effective as a plastic or foil sheet and any damage to the painted surface reduces its ability to reduce the amount of moisture getting through.
• Rolls of basic clear or black polyethylene plastic sheeting thick enough (usually single ply and at least 6-mil thick ) to be used as a vapor barrier --in walls, flooring, ceilings or under concrete slabs, start around 5 cents to 20 cents per square foot, or $75 -$300 for 1,500 square feet. This basic plastic sheeting still allows some water and vapor to pass, and tends to tear easily. Thicker (8-mil to 23-mil), multi-ply vapor barriers (often designed for specific uses, such as under concrete slab or between new wood flooring and a concrete subfloor) can cost 25 cents to $1.50 a square foot, or $375 -$2,250 for 1,500 square feet. In many cases these vapor barriers are installed as part of a larger project; if done by a contractor, the vapor barrier will be included in the overall cost. The Energy Efficiency Manual gives an overview of vapor barriers and illustrates the installation of clear poly as a vapor barrier in the new construction of a large master bedroom.
• Another common usage of a vapor barrier, especially in the Southeast and Northeast, is in the crawlspace under a home. This involves laying flat polyethylene plastic of at least 6-mil, on the crawlspace floor, with about 6 inches extending up the walls. All seams are sealed with special tape. Do-it-yourself materials for a 1,500-square-foot crawlspace start around $100 -$400 for basic supplies, and go up for higher-quality materials designed specifically to be used as a vapor barrier. The U.S. Department of Energy recommends using 6-mil polyethylene, overlapping all seams by at least 12 inches, taping all seams and sealing the poly 6 inches up the crawlspace walls, with an optional 2 inches of concrete poured over the poly. Hiring someone to install this in a 1,500-square-foot crawlspace could cost $1,000 -$3,000 or more for labor and materials.
• Crawlspace encapsulation uses a multi-layer 20-mil vapor barrier to completely cover the floor and and walls, while also sealing all crawl space vents and openings, and adding a dehumidifier or sump pump if needed. The total cost with installation is $3,000 -$15,000 or more. See How Much Does Crawlspace Encapsulation Cost.

• Readers' Digest provides illustrated how-to instructions for installing a 6-mil vapor barrier in a crawl space. Vapor barriers work best in primarily cold climates or primarily hot and muggy climates but not mixed climates where it's both extremely cold in winter and quite hot and humid in summer. The U.S. Department of Energy provides an overview of vapor barriers.

• Rolls of basic 6-mil polyethylene sheeting are available at hardware and home improvement stores like Home Depot, and from online sellers such as Amazon. They also sell vapor barriers designed for specific purposes, such as under laminate flooring.
• For thicker and higher-quality vapor barriers designed for other uses, check stores that sell concrete supplies to contractors. CrawlSpaceInfo.com sells rolls of 8-mil, 12-mil and 20-mil DrySpace vapor barriers designed to be used in crawl spaces (and offers installation in some areas); BasementSystems.com offers referrals to contractors authorized to install it seven-layer, 20-mil encapsulation systems (but does not sell the vapor barrier product direct to consumers).
• Major manufacturers of vapor barriers include Carlisle, ePro Waterproofing Systems and Fortifiber.

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