In veneer backing, what is the purpose of a drainage plane within the structure?

• A. To insulate the wall.
• B. Directs moisture away from the veneer and helps manage drainage.
• C. To increase mass of the wall.
• D. To prevent any air movement.

Answer: (B)

Moisture management behind veneer relies on a drainage plane. This layer creates a small cavity behind the veneer that directs any water that gets through the outer layer downward and out of the wall, while still allowing air to circulate to help the assembly dry. By giving water a dedicated path to drain, it prevents liquid moisture from wicking into the backing and substrate, reducing the risk of rot, staining, and mold, and it helps minimize freeze‑thaw damage by keeping the veneer relatively dry. It’s not about insulation or adding mass, and it doesn’t aim to stop air movement; rather, it works with a controlled air space to dry the wall system.