Where roofs meet walls, water problems are common. Roof-to-wall connections direct significant runoff against the siding, and siding alone isn’t designed to handle that. If a window sits in the wall, water can find its way into the opening and cause rot quickly. Repair costs can be steep. The fix is cheap and direct: kickout flashing.
It’s available at most home centers and online. It can also be made on-site from a piece of step flashing and a pair of needle-nose pliers.
How the Detail Works
Kickout flashing sits at the base of a roof where it meets a wall. Instead of letting water run down the wall face, it diverts that flow outward onto the roof or into a gutter. Without it, water can work behind siding and into the wall cavity over years.
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According to a design-build firm in the Pacific Northwest, Hammer & Hand, the installation follows a sequence that works with mechanically fastened weather-resistive barriers (WRB). The process is even simpler with peel-and-stick or fluid-applied housewraps.
Installation Sequence (Simplified)
Start with a starter strip along the bottom of the roof. Place the kickout flashing in the position of the first step flashing at the base. Then install the first course of shingles. Place step flashing, overlapping the previous piece by about 2 inches, aligning the top with the shingle. Apply a flashing membrane or peel-and-stick housewrap over that step flashing. Cut a slit for the kickout. Leave a 2-inch gap between the membrane and the roofing.
Overlap the housewrap onto the flashing legs, again with a slit for the kickout, and maintain a 2-inch gap above the roofing. Then install siding as normal, keeping the bottom edge a couple of inches above the roof — regardless of siding type. Finally, install a gutter behind the drip edge to collect the water and send it into the downspout.
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One framing tip: Leave a gap between the subfascia and the wall sheathing during framing. This allows the WRB and flashing to slide behind before the fascia goes on, improving water management from the start.
You Can Make One On-Site in Under a Minute
If you don’t want to buy a prefab unit, you can bend one yourself. Grip the upturned leg of a step flashing piece with needle-nose pliers, perpendicular to the fold. Rotate the pliers counterclockwise to twist the bottom leg — the part that sits on the roof — away from the wall to form a diverter. Flatten the fold with a hammer. In a few minutes, you’ll have a functional kickout flashing.
What It Costs
Prefabricated options are available from several suppliers. Masonrydirect.com sells a universal kickout flashing by Demand Products for $19.74. Kickoutflashing.com offers a powder-coated bronze version in four colors for $22 each, with bulk pricing available.
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The materials for a DIY version cost only the price of a single step flashing piece, which runs a few dollars. Add a pair of needle-nose pliers if you don’t already have them.
Kickout flashing isn’t glamorous. It’s a small piece of metal or plastic that sits where roof and wall meet. But it does one job consistently: keeping water out of a vulnerable joint. For homeowners, builders, or inspectors, it’s a cheap detail that pays for itself the first time it works.
