Frequently Asked Questions
What is HOUSEWRAP?
Why use a HOUSEWRAP?
What does a HOUSEWRAP do?
How does a HOUSEWRAP work?
Why is it important for walls to breathe?
Can you use HOUSEWRAPS under any exterior façade?
Do HOUSEWRAPS really improve the energy efficiency of the building?
Do HOUSEWRAPS have an R-value?
How does a HOUSEWRAP differ from Grade D building paper?
Will using HOUSEWRAP prevent mold growth?
Are there different types of Housewrap?
Like a windbreaker jacket you zip up on a chilly day, housewrap is a protective barrier against the elements. Installed behind an exterior cladding, they protect an exterior wall from exposure to water that penetrates the exterior covering, and prevent air leakage in a building.
Housewraps enhance the heating and cooling efficiency of a building by controlling air leakage and infiltration. They improve the quality of indoor air by blocking external pollutants from odors to biological contaminants. Housewraps protect the wall system from water and moisture damage, which could potentially lead to mold or mildew or even rot and degradation of wall system materials.
Housewraps protect buildings from drafts, conditioned-air leakage, and water. All housewraps function as air retardants and control air leaks through wall systems. Some housewraps, like HomeGuard HP or LP Plus Housewrap, meet the requirements for an Air Barrier Material (0.02 L/s⋅m2 @ 75 Pa OR 0.004 cfm/ft2 @ 1.57psi), which reduces air permeance. Housewraps that do qualify as air barrier materials must be installed in strict accordance with the manufacturer’s instructions in order to perform as required.
Housewrap decreases air infiltration into the wall cavity. This allows the insulation to function properly by trapping air and creating a dead air space.
Housewraps also resist bulk water penetration resulting from wind-driven rain that penetrates the exterior cladding and can ultimately migrate into a well-built wall cavity. Housewraps enable walls to dry out by allowing moisture vapor to escape when liquid water evaporates.
An average home creates three to six gallons of moisture vapor every day from cooking, showering even breathing. If moisture vapor becomes trapped in the wall cavity of a building, as the temperature drops outside the vapor turns to liquid water. This water can potentially lead to growth of mold or mildew and cause rotting or rusting of building materials.
Housewraps are used under most exterior cladding materials. In fact, the International Building, Residential and Energy Codes require the use of a water-resistive barrier (Housewrap or felt building paper) in exterior walls. Most housewraps are not appropriate for all exterior facades, but HomeGuard HP or LP Plus housewrap is specified and approved for use behind EIFS, stucco, cement, hardboard, vinyl, wood siding, brick and stone veneer.
Yes. The average 2500 square foot house (232m2) has more than ½ mile (806m) of cracks and crevices, which are open to wind and wind driven rain. A properly installed Housewrap system, which includes proper flashing and seals, will vastly improve the overall thermal efficiency and performance of the building’s wall system.
Housewraps have no intrinsic R-value. However, they enhance the thermal performance of a wall system by reducing air leakage in the wall system.
Most commercially available polymeric Housewraps are highly moisture-resistant and therefore do not absorb water like typical Grade D or felt building papers. Polyolefin Housewraps are typically stronger than Grade D or felt building papers, thus they tend to have better durability than conventional building papers (paper-based) or felt building paper.
Housewraps that are made from a plastic or spun-fiber polyethylene textile material, like HomeGuard Housewraps, are recognized as not providing a food source for fungus, mold, mildew or insects. Furthermore, Housewrap will block rain from soaking the walls and it is breathable to allow moisture vapor to escape. The ability to breathe is what allows the wall cavity to dry thoroughly and inhibits the growth of mold.
Yes. Housewraps can be woven or non-woven, moisture permeable or moisture non-permeable, translucent or opaque, UV Resistant or not. It is important to choose the correct housewrap material for the correct job.
For more information on housewraps, air barriers, testing methods and standards visit these websites:
- ABAA Air Barrier Association of America
- ASHRAE – American Society of Heating, Refrigerating and Air-Conditioning Engineers
- IECC – International Energy Conservation Code