Water-Resistive Barrier (WRB)

Definition

A Water-Resistive Barrier (WRB), also referred to as a "Weather-Resistive Barrier," is a primary building envelope sealed barrier. Seams and fasteners are taped to defend the exterior envelope from water intrusion.

Purpose

The purpose of a WRB is to prevent water from penetrating the building envelope while allowing water vapor to escape. It enhances the building's durability and energy efficiency by protecting against moisture-related damage.

Examples of Use

• Exterior Walls: Installed behind siding or other cladding materials to prevent water infiltration.
• Roofs: Used as an underlayment beneath roofing materials to protect against leaks.
• Windows and Doors: Sealed around openings to prevent water from entering the building.

Related Terms

• House Wrap: A type of WRB used in residential construction, such as Tyvek or Typar.
• Building Envelope: The physical separator between the interior and exterior of a building.
• Flashing: Material used to direct water away from critical areas of the building envelope.

Notes

Proper installation of WRBs is crucial for effectiveness. All seams, edges, and penetrations must be properly sealed to ensure a continuous barrier against water intrusion.