How should the flashing be done at the bottom of a brick veneer wall where it sits on the foundation ledge?

Through-wall flashing at the foundation ledge is critical. It must collect water that penetrates the veneer and direct it out via weep holes.

Correct Assembly (Bottom Up):

1. Foundation Ledge: Clean, mortar-free, sloped slightly outward (min. 1/4" per ft) or level with a positive slope to the exterior face.
2. Flashing Membrane: Extend up the backup wall minimum 8" (IRC R703.8.1 / TMS 402). Turn up the interior face of the veneer minimum 6" (TMS 402 Sec. 6.3.2.2) or to the height of the first course of brick. Do not stop at the ledge face.
3. Material: Copper, stainless steel, or high-quality self-adhered rubberized asphalt (40-mil min.). Avoid PVC/vinyl (UV degradation, brittleness). Lap seams 6" minimum, shingle-lap style (uphill over downhill). Seal laps per manufacturer (mastic/tape).
4. Drip Edge: Mandatory. Flashing must project minimum 1/4" beyond the exterior face of the foundation/veneer (IRC R703.8.2.1). Hemmed metal drip edge preferred; formed membrane drip acceptable if stiffened.
5. End Dams: Required at all terminations (corners, openings, intersections). Turn flashing up vertically minimum 4" against backup/side walls. Seal to backup.
6. Weep Holes: Required immediately above flashing (IRC R703.8.2.1). Open head joints (no mortar) at 24" o.c. max (16" o.c. preferred). Or use plastic/metal vents/tubes. Keep clear of mortar droppings (use mesh vents or "mortar net" at cavity bottom).
7. Protection Board: Cover flashing on backup wall with rigid insulation or protection board before brickwork to prevent damage.
8. Mortar Net/Cavity Drain: Install mesh/mortar net at cavity bottom (first 4–8") to keep weeps clear.

Key Code Refs: IRC R703.8 (Flashing), R703.8.1 (Location), R703.8.2.1 (Weeps/Drip), TMS 402/602 Sec. 6.3 (Flashing Details).

Common Failures: Flashing stopped at ledge face (water runs back in), no drip edge (water tracks back under brick), no end dams (water leaks sideways), weeps clogged/omitted.

Note: If the ledge is not level/sloped out, correct it before flashing. This detail requires precision; if unsure, consult a masonry specialist or architect.

For a brick veneer wall resting on a foundation ledge, proper flashing at the base is critical to prevent water intrusion and ensure long-term durability. Follow these steps per IRC (International Residential Code) and industry best practices (e.g., BIA Technical Notes 7 and 28):

1. Install a continuous water-resistive barrier (WRB) over the sheathing, extending down and onto the foundation ledge or concrete slab. Lap the WRB a minimum of 6 inches over the top of the flashing membrane (IRC R703.1).

1. Apply through-wall flashing at the shelf angle or foundation ledge. Use a durable, corrosion-resistant material such as: - Self-adhered rubberized asphalt membrane (minimum 40 mils thick), - Copper (minimum 16 oz), - Stainless steel, or - PVC-composite flashing. Extend the flashing at least 8 inches up the backup wall and 6 inches out over the foundation ledge (or onto the slab), with a drip edge formed to shed water away from the wall (BIA TN 7).

1. Create a dam and weep system: - Turn the flashing up at the backup wall to form a dam (minimum 2 inches high) to prevent water from migrating behind the veneer. - Install open head joint weeps every 24 inches (or wick/rope weeps every 16 inches) directly above the flashing to drain any water that enters the cavity (IRC R703.4). - Keep weeps clear of mortar droppings using a mortar net or similar device.

1. Support the veneer on a non-corrosive, load-bearing shelf angle or concrete ledge. Ensure the brick veneer bears on the flashing or a compatible bearing pad — never directly on flexible flashing alone.

1. Seal terminations where flashing meets windows, doors, or penetrations with compatible sealant or termination bars to maintain continuity.

Critical: Flashing must be continuous and unbroken. Avoid punctures or improper lapping. If the foundation ledge is concrete, ensure it is smooth, clean, and free of protrusions that could damage the flashing.

Note: If the wall exceeds standard heights or involves complex geometries (e.g., curved walls, seismic zones), consult a structural engineer or licensed architect. For most residential applications, this method meets code and prevents moisture-related damage.

Always verify local amendments to the IRC and follow manufacturer specifications for flashing and WRB products.