Ads
related to: 12 mil polyethylene vapor barrier wallsinsulation4less.com has been visited by 10K+ users in the past month
Search results
Results From The WOW.Com Content Network
A vapor barrier on the warm side of the envelope must be combined with a venting path on the cold side of the insulation. This is because no vapor barrier is perfect, and because water may get into the structure, typically from rain. In general, the better the vapor barrier and the drier the conditions, the less venting is required. [7]
Polyethylene vapor barriers are risky except in frigid climates because they limit the wall's ability to dry to the interior. This approach also limits the amount of interior insulation that can be added to a relatively small amount (e.g., only R-6 insulation can be added to a 2×4 R-12 wall).
Housewrap functions as a weather-resistant barrier, preventing rain or other forms of moisture from getting into the wall assembly while allowing water vapor to pass to the exterior. If moisture from either direction is allowed to build up within stud or cavity walls, mold and rot can set in and fiberglass or cellulose insulation will lose its ...
Air barriers control air leakage into and out of the building envelope.Air barrier products may take several forms: Mechanically-attached membranes, also known as housewraps, usually a polyethylene-fiber or spun-bonded polyolefin, such as Tyvek is a generally accepted moisture barrier and an air barrier (ASTM E2178).
In order to achieve these objectives, all building enclosure systems must include a solid structure, a drainage plane, an air barrier, a thermal barrier, and may include a vapor barrier. Moisture control (e.g. damp proofing ) is essential in all climates, but cold climates and hot-humid climates are especially demanding.
It is important to realise a single R-value or U-value does not take into account the quality of construction or local environmental factors for each building. Construction quality issues can include inadequate vapor barriers and problems with draft-proofing. In addition, the properties and density of the insulation material itself are critical.
Ad
related to: 12 mil polyethylene vapor barrier walls