Ads
related to: class 1 vapor retarder thickness
Search results
Results from the WOW.Com Content Network
American building codes started classifying vapor retarders in the 2007 IRC supplement. They are Class I <0.1 perm, Class II 0.1 - 1 perm and Class III 1-10 perm when tested in accordance with the ASTM E96 desiccant, dry cup or method A. [1] Vapor-retarding materials are generally categorized as:
Moisture vapor transmission rate (MVTR), also water vapor transmission rate (WVTR), is a measure of the passage of water vapor through a substance. It is a measure of the permeability for vapor barriers. There are many industries where moisture control is critical.
Tyvek is a nonwoven product consisting of spun bond olefin fiber.It was first discovered in 1955 by a researcher for the DuPont textile company working in an experimental lab, who noticed a type of white fluff coming out of a pipe. [2]
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). Self-adhered membranes, which are typically also a water-resistant barrier and a vapor barrier
Open-cell foam is porous, allowing water vapor and liquid water to penetrate the insulation. Closed-cell foam is non-porous, and not moisture-penetrable, thereby effectively forming a semi-permeable vapor barrier. (N.B., vapor barriers are usually required by the Building Codes, regardless of the type of insulation used.
Condensation will not occur, provided that (a) the insulation surface is above the dewpoint temperature of the air; and (b) the insulation incorporates some form of water-vapour barrier or retarder that prevents water vapour from passing through the insulation to form on the pipe surface.
Ads
related to: class 1 vapor retarder thickness