What is kick-out flashing?

Kick-out flashing (also called a roof-to-wall diverter) is a small metal piece installed at the junction where a roof line intersects with a sidewall. Its job is simple but critical: redirect water that runs down the roof slope away from the wall surface and into the adjacent gutter system.

Without proper kick-out flashing, roof runoff flows directly behind the siding, where it soaks the wall framing, house wrap, and insulation. This moisture causes rot, mold growth, and structural damage that can take years to become visible. Once water gets behind the siding, repairs often require removal of exterior cladding and replacement of framing materials.

The flashing is typically L-shaped or boot-shaped, with one arm laid under the roof shingles and the other extending down the wall surface. It must be properly sealed with roofing cement and integration with adjacent flashing to prevent water from finding gaps. Common installation locations include where two-storey walls meet roof lines, above garage roofs that adjoin upper walls, and dormers.

Because this flashing sits at a vulnerable interface where three building elements meet (roof, wall, and gutter), even small gaps or misalignment can lead to significant leaks. Proper installation and maintenance of kick-out flashing is essential in Ontario's climate, where freeze-thaw cycles and heavy seasonal rainfall stress these connections. Many homeowners only discover flashing problems after damage has already started. Qualified roof-repair contractors know how to identify failing kick-out flashing and restore these critical details before serious damage develops.