Did you know that water that enters a building assembly must be directed back out? Through wall flashing is an essential component that collects infiltrated water and safely directs it out of the wall system.
This detail occurs at exterior wall penetrations and other critical transitions to help prevent water from entering the building structure, which could lead to structural damage or mold growth.
Through-wall flashing is typically made from corrosion-resistant sheet metal that can be bent into various shapes and sizes depending on the project conditions.
The low point of the flashing begins at the exterior face of the wall assembly, while the high end typically extends up the inside face of the wall sheathing. At this location, the flashing integrates with the AWRB and is adhered using sealants to maintain continuity of the moisture control layer.
Weep holes are generally spaced 24 inches apart at the base of the flashing to allow collected water to exit the wall assembly.
The low point of the through wall flashing should include an additional “kick” at the outer edge to direct water away from the wall surface. This small projection helps prevent water from running back toward the building.
A hemmed edge is commonly used on exposed flashing. Hemming is an edge-bending process in which the edge of the sheet metal is bent completely over itself. This reinforces the edge, conceals burrs and rough edges, and improves the finished appearance.
Proper detailing of through wall flashing ensures that infiltrated water is redirected safely out of the wall assembly. Integration with AWRB layers, correctly spaced weep holes, and properly formed edges all contribute to reliable moisture management and durable wall performance.
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