A protective membrane that shields building assemblies from water infiltration while allowing vapor transmission and air movement control.

Weather Barrier is a protective membrane that shields building assemblies from water infiltration while allowing vapor transmission and air movement control through specialized materials that create continuous protective layers against wind-driven rain and moisture while maintaining breathability for building envelope performance. This essential building envelope component consists of water-resistant membranes, housewraps, or building papers that are installed behind exterior cladding to prevent water penetration while allowing water vapor to escape from wall assemblies. Weather barriers are critical in building construction where they provide secondary water protection, manage moisture movement, prevent air infiltration, and maintain building durability, making them indispensable for exterior wall systems, roofing assemblies, and any application where weather protection is necessary for building envelope performance and occupant comfort.

Weather barriers are utilized in various building envelope applications and construction systems including exterior wall assemblies where they provide backup water protection behind siding, stucco, and masonry cladding, roofing systems where they serve as secondary water barriers under primary roofing materials, window and door installations where they manage water around openings and penetrations, foundation walls where they protect against moisture infiltration, commercial building envelopes where they provide weather protection for curtain walls and panel systems, and specialty applications including green walls, rain screens, and ventilated facades where enhanced weather protection is required for system performance. Each application requires appropriate barrier selection, installation methods, and integration with other building components based on climate conditions and performance requirements.

The types and materials of weather barriers include housewrap products that provide basic water resistance with high vapor permeability, building papers including asphalt-saturated felt and synthetic alternatives that offer traditional weather protection, liquid-applied barriers that create seamless, monolithic weather protection, self-adhering membranes that provide enhanced water resistance and air sealing, permeable membranes that allow vapor transmission while blocking liquid water, and specialty barriers including air and weather barriers that combine multiple functions for enhanced building envelope performance. Material selection depends on climate conditions, building design, and performance requirements.

Fun Fact: The first modern weather barriers were developed in the 1950s using asphalt-saturated felt, and today’s advanced synthetic weather barriers can provide 10 times better water resistance while allowing 5 times more vapor transmission than traditional building papers.

• Weather Resistant Barrier (WRB)
• Air Barrier
• Dust Barrier