6-mil (0.15 mm) polyethylene plastic sheet as vapour barrier between insulation and gypsum boardGlass wool pipe insulation covering a steel pipe as it penetrates a mock-up concrete slab whose opening will be firestopped. In this manner, the vapor barrier (in this case made of foil/scrim/kraft paper, called ASJ, all-service jacket, aluminium on the inside, white paper on the outside) can remain intact as it penetrates the fire barrier.
A vapor barrier (or vapour barrier) is any material used for damp proofing, typically a plastic or foil sheet, that resists diffusion of moisture through the wall, floor, ceiling, or roof assemblies of buildings and of packaging to prevent interstitial condensation. Technically, many of these materials are only vapor retarders as they have varying degrees of permeability.
Materials have a moisture vapor transmission rate (MVTR) that is established by standard test methods. One common set of units is g/m2·day or g/100in2·day. Permeability can be reported in perms, a measure of the rate of transfer of water vapor through a material (1.0 US perm = 1.0 grain/square-foot·hour·inch of mercury ≈ 57 SI perm = 57 ng/s·m2·Pa). American building codes have classified vapor retarders as having a water vapor permeance of 1 perm or less when tested in accordance with the ASTM E96 desiccant, or dry cup method.[1] Vapor-retarding materials are generally categorized as:
Impermeable (≤1 US perm, or ≤57 SI perm) – such as asphalt-backed kraft paper, elastomeric coating, vapor-retarding paint, oil-based paints, vinyl wall coverings, extruded polystyrene, plywood, OSB;
Semi-permeable (1-10 US perm, or 57-570 SI perm) – such as unfaced expanded polystyrene, fiber-faced isocyanurate, heavy asphalt-impregnated building papers, some latex-based paints);
Permeable (>10 US perm, or >570 SI perm) – such as unpainted gypsum board and plaster, unfaced fiber glass insulation, cellulose insulation, unpainted stucco, cement sheathings, spunbonded polyolefin or some polymer-based exterior air barrier films.
^Smart Vapor Retarders. Certain Teed Corporation. 2006. p. 2.
A vaporbarrier (or vapour barrier) is any material used for damp proofing, typically a plastic or foil sheet, that resists diffusion of moisture through...
vapor through a substance. It is a measure of the permeability for vaporbarriers. There are many industries where moisture control is critical. Moisture...
vibration, compression, temperature, bacteria, etc. Barrier protection - A barrier from oxygen, water vapor, dust, etc., is often required. Permeation is a...
for a vaporbarrier or retarder when using cellulose insulation. This appeal cited industry guidance that the combination of an exterior vapor retarder...
to strips of radiant barrier to make it a contiguous vaporbarrier or, alternatively, radiant barrier can be perforated for vapor transmittance. All materials...
vermin) Can serve as a semi-permeable vaporbarrier with a better permeability rating than plastic sheeting vaporbarriers and consequently reduce the buildup...
insulation Thermosiphon Underfloor air distribution Underfloor heating VaporbarrierVapor-compression refrigeration (VCRS) Variable air volume (VAV) Variable...
occur on or to the inside of the vaporbarrier during cold weather. The 1/3:2/3 rule will ensure that the vaporbarrier temperature will not fall below...
moisture barrier and an air barrier (ASTM E2178). Self-adhered membranes, which are typically also a water-resistant barrier and a vaporbarrier Fluid-applied...
tend to rise due to the stack effect. Encapsulation involves adding a vaporbarrier to the floor, sealing off all openings to the outdoors, adding thermal...
control, and vapor control. Control of rain is most fundamental, and there are numerous strategies to this end, namely, perfect barriers, drained screens...
The vapor pressure of water is the pressure exerted by molecules of water vapor in gaseous form (whether pure or in a mixture with other gases such as...
Generally, damp proofing keeps exterior moisture from entering a building; vaporbarriers, a separate category, keep interior moisture from getting into walls...
refrigeration cycles can be classified as vapor compression, vapor absorption, gas cycle, or Stirling cycle types. The vapor-compression cycle is used by many...
which thermal conduction is reduced, creating a thermal break or thermal barrier, or thermal radiation is reflected rather than absorbed by the lower-temperature...
insulation Thermosiphon Underfloor air distribution Underfloor heating VaporbarrierVapor-compression refrigeration (VCRS) Variable air volume (VAV) Variable...
surrounds a F/A-18C at transonic speed F-35 with a double vapor cone Sonic boom Sound barrier Shock diamond Shock wave Contrail Condensation cloud Prandtl–Glauert...
reduces cooling loads. Sometimes an insulated roof with an internal vaporbarrier is preferable to a ventilated attic. In areas with wildfire hazards...
brittle. It is an inexpensive resin per unit weight. It is a poor barrier to air and water vapor and has a relatively low melting point. Polystyrene is one of...
condensation barrier inside walls when installing HVAC systems. It is also used as a ground cover in the crawl space of home foundations as a vaporbarrier. The...
insulation Thermosiphon Underfloor air distribution Underfloor heating VaporbarrierVapor-compression refrigeration (VCRS) Variable air volume (VAV) Variable...
thermally conductive solid surface turns into a vapor by absorbing heat from that surface. The vapor then travels along the heat pipe to the cold interface...
dehumidification; effective vaporbarrier wall sealing; proper insulation; using an diffusion tight vaporbarrier (vapor check) on the warm side of the...
and make the transition from water to vapor. If the vapor then condenses to a liquid on a surface, then the vapor's latent energy absorbed during evaporation...
without vaporbarriers or with dirt floors, are mold-prone. The "doormat test" detects moisture from concrete slabs without a sub-slab vaporbarrier.[citation...
Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity...
Water vapor, water vapour or aqueous vapor is the gaseous phase of water. It is one state of water within the hydrosphere. Water vapor can be produced...
Global Information
