Why is kick-out flashing important?

It prevents roof runoff from dumping behind siding at the bottom of a roof-wall joint. Without it, the wall can stay wet for years before the damage becomes obvious inside or outside the house.

How can I tell if kick-out flashing is missing?

Look for a roof edge that dies into a wall above a gutter with no visible diverter at the bottom. Staining, rot, swollen trim, or repeated paint failure at that exact corner are strong clues that water is bypassing the gutter there.

Can a missing kick-out flashing cause an interior leak?

Yes. Water can run behind the siding, soak the sheathing, and eventually show up as staining or softness inside the wall. By the time interior damage appears, the exterior wall assembly may already have significant decay.

Can a roofer add kick-out flashing without replacing the whole roof?

Often yes, but the repair still has to tie properly into the step flashing and wall weather barrier. Simple surface sealant is not a real substitute, so the exact scope depends on how accessible the joint is behind the siding and roofing.

Kick-Out Flashing — Roof-Wall Water Diverter Guide

Kick-out flashing is an L-shaped roof-wall flashing diverter that sends water from the end of a roof-to-wall intersection into the gutter instead of down the wall.

Kick-Out Flashing diagram — labeled parts, dimensions, and installation context

What It Is

Kick-out flashing is installed where a sloped roof terminates into a vertical wall, usually at the bottom of a run of step flashing. Its job is to catch runoff traveling down the wall-side roof edge and kick that water out into the gutter before it can run behind siding or stucco.

This is a small detail with oversized consequences. When it is missing or poorly shaped, water can repeatedly soak the wall assembly at one concentrated point, leading to rot, mold, peeling paint, stained cladding, and hidden sheathing damage.

Types

Kick-out flashing is usually made from bent aluminum, galvanized steel, copper, or preformed plastic or composite flashing material approved for the wall system. The exact shape varies, but the piece always needs a vertical leg, roof leg, and outward diverter that projects water clear of the wall.

Some roofers fabricate kick-out flashing on site from step-flashing stock, while others use preformed pieces sized to common roof and siding details. The right material depends on the roofing type, nearby metals, and climate exposure.

Where It Is Used

Kick-out flashing is used at the bottom of a roof-to-wall intersection where shingles and step flashing end above a gutter. It is common beside chimney chases, second-story sidewalls, dormers, and porch roofs that die into a taller exterior wall.

It is especially important on stucco, fiber-cement, engineered wood, and other claddings that can trap moisture behind the surface. Even a well-installed gutter cannot protect the wall if the roof runoff is never kicked into the gutter opening.

How to Identify One

Look at the lowest point where a sloped roof edge meets a wall above an eave gutter. A proper kick-out flashing will appear as a small bent metal diverter that flares away from the wall and points runoff into the gutter.

If you see staining, rot, swollen trim, peeling paint, algae streaks, or missing siding clearance at that location, a missing or undersized kick-out flashing is a common cause. This detail is often easiest to inspect from a ladder or in photos taken at the eave line.

Replacement

Replacement is needed when the diverter is missing, rusted, crushed, too short to reach the gutter, or buried behind siding in a way that still allows water into the wall. Correcting it often requires loosening siding or trim and integrating the new piece with the step flashing and housewrap, not just surface-caulking the area.

Because kick-out flashing works as part of a full water-management assembly, repairs are best handled during reroofing, siding repair, or targeted leak correction. The surrounding gutter, drip edge, and siding clearance should be evaluated at the same time.