Housewrap (or house wrap), also known by the

genericized trademark A generic trademark, also known as a genericized trademark or proprietary eponym, is a trademark or brand name that, because of its popularity or significance, has become the generic term for, or synonymous with, a general class of products ...

homewrap (or home wrap), generally denotes a modern synthetic material used to protect buildings. Housewrap functions as a weather-resistant barrier, preventing rain or other forms of moisture from getting into the wall assembly while allowing

water vapor (99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 J/( kg·K) , - , Heat of vaporization , 2.27 MJ/kg , - , Heat capacity , 1.864 kJ/(kg·K) Water vapor, water vapour or aqueous vapor is the gaseous p ...

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 Fiberglass ( American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cl ...

or cellulose insulation will lose its R-value due to heat-conducting moisture. House wrap may also serve as an air barrier if it is sealed carefully at seams. Housewrap is a replacement for the older tar paper or asphalt saturated felt on walls. It is lighter in weight, available in much wider rolls, and both faster and easier to apply.

Major types

* Micro-perforated, cross-lapped films * Films laminated to spunbond nonwovens (Typar or CertaWrap) * Films laminated or coated to

polypropylene Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer propylene. Polypropylene belongs to the group of polyolefins a ...

wovens *

Supercalendered A calender is a series of hard pressure rollers used to finish or smooth a sheet of material such as paper, textiles, rubber, or plastics. Calender rolls are also used to form some types of plastic films and to apply coatings. Some calend ...

, wetlaid

polyethylene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging ( plastic bags, plastic films, geomembranes and containers including b ...

fibril nonwoven (" Tyvek") *

Installation

Housewrap must be both water shedding and have a high moisture vapor transmission rate (MVTR) to be effective. It must also take handling abuse during installation and, as housewrap is often left exposed for some time after construction awaiting exterior siding installation, be resistant to UV. 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. Most newer designs do not "seal" well against nails or staples like asphalt products. Housewrap is installed between the sheathing and the exterior siding, and is utilized behind vinyl, wood clapboards, shingles or shakes, brick, and other building materials. In all cases, the housewrap helps prevent water intrusion when moisture in any form gets past the siding and its trim and caulking.

Properties

* Typical MVTR ~200 grams/100 square-inches/24hours (or greater, i.e., Tyvek is ~400) * Typical 2 ounces/square-yard (varies greatly with manufacturer) * Typical width 9' (108)" on a 3" core

References

{{reflist Moisture protection Building materials