Brick veneer walls must include a continuous drainage plane behind the cladding to prevent moisture accumulation, freeze-thaw damage, and deterioration of inner wall components. This article outlines best practices for detailing cavity spacing, flashing, and weep systems in residential and commercial veneer assemblies.
Drainage Cavity Design Guidelines
- Maintain a minimum 1-inch clear air space between veneer and sheathing or WRB
- Use cavity drainage mesh or mortar droppings collector at base of wall
- Ensure no insulation or membrane protrudes into the cavity space
- Tie WRB and air barrier into cavity flashing with shingle-style lap
Flashing at Base, Lintels, and Openings
Install through-wall flashing above foundations, shelf angles, and lintels. Flashing should extend full depth of the cavity and be turned up 6–8 inches on the back wall. End dams, corner patches, and sealant terminations are required. Terminate flashing beneath weep vents or open-head joints every 24–32 inches on center.
Material Compatibility and Code Requirements
- Use non-corrosive flashing materials such as copper, stainless steel, or polymer composites
- Comply with ASTM C1063, BIA Technical Notes 7 and 7A
- Install weeps per local code, no higher than the first course above flashing
- Ensure proper slope of shelf angles and flashing toward weep face
Quality Control and Mockups
- Inspect cavity depth and cleanliness prior to veneer installation
- Ensure flashing fully wraps inside corners and laps past ends of lintels
- Weeps must be open and unobstructed after brick installation
- Mockups should include all flashing and weep components for early review
Field photos should document flashing installation prior to brick placement for warranty and inspection purposes.
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Advanced Detailing Tips
For added performance, include a termination bar with sealant above through-wall flashing to secure and seal the WRB at cavity transitions. Use stainless steel drip edges on exposed flashing to improve durability and aesthetics, particularly above window heads and shelf angles.
Install pre-molded inside and outside corner boots at all flashing changes in direction. Ensure corner seams are overlapped and taped or fluid-sealed. Brick ties must not compress the drainage mesh or restrict cavity airflow—use standoff anchors or thermal isolators where applicable.
Thermal Bridging Considerations
To reduce thermal bridging at shelf angles, use thermal break pads between masonry support and structural steel. Coordinate insulation continuity from the backup wall to the cavity face using mineral wool inserts or spray-applied foam within shelf angle returns. Ensure cavity insulation is not in direct contact with wet mortar or debris.
