Brick Veneer Leakage at a Shelf Angle
A four-story wood-framed building has a brick veneer exterior. The veneer has a 2-inch air space, corrugated steel ties, and a drainage plane. Ties are fastened to studs at 16 inches on center vertically and 24 inches on center horizontally. The base flashing laps the housewrap by only 2 inches and is not taped. There are no weeps over the shelf angle at the third floor, and at the same elevation the mortar bed bridges the air space for about 30 feet. A few ties are nailed through the sheathing only, but most engage studs. After wind-driven rain, drywall stains appear on the third and fourth floors, and efflorescence blooms on the brick below the shelf angle. The masonry contractor says the tie spacing is the primary problem because the ties exceed 16 inches on center both ways and should be 16 inches on center horizontally and vertically.
1. Is the contractor correct that tie spacing is the primary problem? Explain.
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No. The reported spacing is 16 inches vertically by 24 inches horizontally. The contractor's claim that the ties exceed 16 inches both ways is incorrect; the vertical spacing is 16 inches, and the horizontal spacing is 24 inches. That pattern is a common maximum for veneer ties and is not by itself the likely cause of widespread third- and fourth-floor staining. The few ties fastened only through sheathing are a local defect and should be corrected, but they do not explain a leak pattern concentrated at the third-floor shelf angle. The contractor is focusing on a compliant spacing while overlooking the water-management details that match the symptoms.
2. Rank the water-management defects by likelihood of causing the interior stains and justify your ranking.
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First are the missing weeps and the mortar bridging at the third-floor shelf angle. Bridging blocks drainage and can dam water at the angle; without weeps, that water has nowhere to exit and can move inward. Second is the base flashing lap of only 2 inches, untaped, which can allow water to get behind the drainage plane. Third are the ties nailed only through sheathing, which are localized and more of a structural attachment issue than a primary leak path. The efflorescence below the shelf angle supports the diagnosis that water is being trapped and migrating through the brick at that elevation, not that the uniformly spaced ties are the main cause.
3. What repair sequence and verification would you require?
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Remove the brick immediately above and below the shelf angle, clear the mortar bridging, and verify that the flashing is continuous and properly lapped and taped to the drainage plane. Install weeps at the required spacing over the flashing and at the base, and correct any ties that do not engage studs. Rebuild the veneer with a clear air space and proper flashing details. After repair, perform a water test on the repaired area, such as a spray test per ASTM E1105, and inspect the interior side for leakage. Also inspect other shelf angles and floor lines for the same bridging and missing weeps. Do not rely on repainting the drywall or applying a surface sealer as the primary repair.