Drainage Cavity/Air Gap

Definition

The space between the backside of the veneer and the weather-resistive barrier to aid in drying the exterior surface of the building envelope wall system.

Purpose

A drainage cavity or air gap helps manage moisture by allowing water that penetrates the veneer to drain away and by promoting air circulation to dry the wall system. This prevents water damage, mold growth, and deterioration of building materials.

Examples of Use

1. Brick Veneer Walls: Installed behind brick veneers to manage moisture and enhance durability.
2. Stucco Systems: Used in stucco applications to prevent moisture buildup and allow proper drying.
3. Rain Screen Systems: An essential component of rain screens, providing an air gap that enhances water drainage and wall ventilation.

Related Terms

• Weather-Resistive Barrier (WRB): A material that resists water infiltration and allows vapor to escape, used in building envelopes.
• Weep Holes: Small openings in a wall that allow water to drain out from behind the veneer.
• Flashings: Thin pieces of material installed to prevent water penetration at joints and seams in building exteriors.

Notes

• Proper installation of drainage cavities is crucial to the effectiveness of the building envelope in managing moisture.
• Regular inspection and maintenance help ensure the cavity remains clear and functional.