Which barrier sheds moisture from the exterior, restricts water entry, and also acts as a wind barrier in the wall assembly?

• A. Thermal Barrier
• B. Weather/Wind Barrier
• C. Air Barrier
• D. Vapour Barrier

Answer: (B)

Weather barrier, often called a weather-resistive barrier, is the layer in a wall assembly that sheds exterior moisture, prevents water entry, and also acts as a wind barrier by reducing air infiltration. It sits behind the cladding and ahead of the sheathing and insulation, blocking rain-driven water while allowing the wall to dry through vapor diffusion. That combination fits the described roles: moisture shedding, water entry restriction, and wind protection. The other options focus on one aspect—thermal performance, vapor diffusion, or air leakage—but do not primarily provide all three functions together.