# Housewrap > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Housewrap > Markdown URL: https://mediated.wiki/source/Housewrap.md > Source: https://en.wikipedia.org/wiki/Housewrap > Source revision: 1335341421 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) Material used to protect buildings This article needs more citations. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Housewrap" – news · newspapers · books · scholar · JSTOR (August 2008) (Learn how and when to remove this message) A building wrapped with [Tyvek](/source/Tyvek)-brand housewrap during construction **Housewrap** (or **house wrap**), also known by the [genericized trademark](/source/Genericized_trademark) **homewrap** (or **home wrap**), generally denotes a modern [synthetic material](/source/Synthetic_fiber) used to protect buildings. Housewrap functions as a water-resistant layer, preventing rain or snow from getting into the wall assembly while allowing [water vapor](/source/Water_vapor) to pass to the exterior. Housewraps can only be exposed for a few months, as it is not a weather resistant layer, and weather elements including sunlight and temperature, can damage it. Furthermore housewraps are not a form of insulation. If moisture from either direction is allowed to build up within stud or cavity walls, [mold](/source/Mold_(fungus)) and [rot](/source/Decomposition) can set in and [fiberglass](/source/Fiberglass_insulation) or [cellulose insulation](/source/Cellulose_insulation) will lose its [R-value](/source/R-value_(insulation)) because of the heat-conducting moisture. House wrap may also serve as an [air barrier](/source/Air_barrier) if it is sealed carefully at seams and supported to resist wind loads.[1] Housewrap is a replacement for the older [tar paper](/source/Tar_paper) or [asphalt saturated felt](/source/Bituminous_waterproofing) on walls. It is lighter in weight, available in much wider rolls, stronger, and both faster and easier to apply. ## Major types - [Nonwoven fabric](/source/Nonwoven_fabric) - Micro-perforated, cross-lapped films - Films laminated to spunbond nonwovens (Typar or CertaWrap) - Films laminated or coated to [polypropylene](/source/Polypropylene) wovens - [Supercalendered](/source/Supercalendered), wetlaid [polyethylene](/source/Polyethylene) fibril nonwoven ("[Tyvek](/source/Tyvek)") ## Installation Housewrap is installed between the sheathing and the exterior siding, and is used behind vinyl, wood clapboards, shingles or shakes, brick, and other building materials. In all cases, the housewrap helps prevent water intrusion when liquid water gets past the siding and its trim and caulking. As such, housewrap must be both water shedding and have a high [moisture vapor transmission rate](/source/Moisture_vapor_transmission_rate) (MVTR) to be effective.[2] It must also withstand abuse during installation, and because housewrap is often left exposed for some time before being cladded-over, it must hold up to wind and resist [UV](/source/UV) for 30 to 90 days. Some new designs must be installed carefully or they will slightly rip or tear during installation, possibly allowing for water infiltration at the damaged areas. Being both thin and inelastic, most newer designs do not "self-seal" well against nails or staples like asphalt products. While housewrap functions as a water-resistive barrier (WRB), it does not automatically serve as a continuous air barrier unless seams, fasteners, and penetrations are properly sealed. Air leakage control depends on installation detailing rather than the membrane material alone.[3] ## Properties - Typical MVTR ~200 grams/100 square-inches/24hours (or greater, i.e., [Tyvek](/source/Tyvek) is ~400) - Typical 2 ounces/square-yard (varies greatly with manufacturer) - Typical width 9' (108)" on a 3" core ## References 1. **[^](#cite_ref-Krigger/Dorsi_121_1-0)** Krigger, John; Chris Dorsi (2004). *Residential Energy: Cost Savings and Comfort for Existing Buildings*. [Helena, Montana](/source/Helena%2C_Montana): Saturn Resource Management. p. [110](https://books.google.com/books?id=7HlKF4trR-YC&pg=PA110). [ISBN](/source/ISBN_(identifier)) [1-880120-12-7](https://en.wikipedia.org/wiki/Special:BookSources/1-880120-12-7). [OCLC](/source/OCLC_(identifier)) [56315804](https://search.worldcat.org/oclc/56315804). 1. **[^](#cite_ref-2)** Reed, Ryan (May 2004). ["Housewrap Felt or Paper: Comparing specs on weather barriers"](https://web.archive.org/web/20040820180108/http://www.buildernewsmag.com/viewnews.pl?id=21). *BUILDERnews Magazine*. Pacific NW Publishing, Inc. Archived from [the original](http://www.buildernewsmag.com/viewnews.pl?id=21) on 2004-08-20. Retrieved 2016-02-24. 1. **[^](#cite_ref-3)** ["Housewrap vs Air Barriers: Understanding the Difference in Building Enclosures"](https://r-valueassociates.com/blog/housewrap-vs-air-barriers/). *R-Value Associates*. --- Adapted from the Wikipedia article [Housewrap](https://en.wikipedia.org/wiki/Housewrap) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Housewrap?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.