Vapor retarder

Vapor retarder

Layer that inhibits vapor diffusion through a building envelope. Examples include polyethylene sheeting, foil facing, kraft paper facing on batt insulation, and low-permeability paints. Most building codes define a vapor retarder as 1 perm or less, with many common vapor retarders being significantly less than 1 perm.

vapor retarder

1. A membrane covering the outer surface of an insulated cold water pipe that is used to prevent moisture from penetrating the insulation and reaching the pipe.
2. A layer of material or laminate used to reduce, appreciably, the flow of water vapor into a roofing system.
References in periodicals archive ?
If there is no vent in the vicinity, check the band joists and, if they are not fully insulated, please do so by placing R-19 fiberglass or Roxul insulation tightly against the band joists throughout the crawl space and staple a plastic vapor retarder to the floor sheathing, the sides of the joists and the mud sill in each space to protect the insulation from moisture migration.
The code language states "in Climate Zones 5, 6, 7 and 8 any air-impermeable insulation shall be a Class II vapor retarder.
now offers Wall Guardian FW-100A, a liquid-applied fibered acrylic air barrier that also acts as a water/weather barrier and vapor retarder.
Later he joined the JM Roofing Division, where he received a patent for a fire-rated vapor retarder system and co-developed other patented products.
The plywood that is likely to be the subfloor under the hardwood floor is an effective vapor retarder and all you need.
From the exterior to the interior, the studied wood-framed wall, shown in Figure 3, is comprised of cement based plaster, a layer of wall membrane, oriented strand board (OSB), cellulose fiber, a layer of vapor retarder and gypsum board.
One common insulation system is a layer of fiberglass insulation laminated to a water vapor retarder that is pulled across the top of the purlins (or outside of the girts)--conventionally referred to as "over-the-purlin" or "over-the-girt" (OP or OG) systems (also, "single layer" systems) within Standard 90.
We recommend filling the stud spaces with friction-fit fiberglass batts, covering the walls and ceiling with a 4-mil poly vapor retarder, and blowing insulation (cellulose insulation is a good choice) into the attic after the ceiling drywall is installed.
To preserve the vapor retarder while housing the building's heating, power and communications distribution systems, an interior utility chase is provided within the exterior walls.
The change allows unvented roof assemblies if two conditions are met: there's no vapor retarder between the attic and the home's living space, and the builder insulates between the rafters with air-impermeable insulation.
Should the vapor retarder be placed next to or external to the insulation?