Kickout flashing (also called diverter flashing) is a short, angled piece of metal or molded plastic installed at the bottom of a roof-to-wall intersection, where a lower roof’s eave runs into a taller wall. It sends the water running down the step flashing out into the gutter. When it is missing, that water pours behind the siding at one corner, and the wall below can rot for years before anyone sees a stain. This page is general information; your roofer and building department make the final call.
On this page: Signs · Causes · Ground check · Fixes · Code basis · When to call
Signs a kickout is missing or failing
- A vertical stripe of stained, swollen or peeling siding running down from a corner where a roof meets a wall.
- Mold or rot at the base of that wall, often near a door or window below.
- Interior stains on the wall or ceiling under the eave.
- Rot found at the bottom of the wall when siding is opened for another reason.
Why it happens
- Never installed. Older homes, and some newer ones, simply lack them.
- Undersized or homemade. The U.S. Department of Energy’s building science guidance notes that site-built kickouts bent from sheet metal can be undersized with unsealed seams that leak, and prefers prefabricated, seamless or welded units.
- Not tied into the weather barrier. DOE warns that a kickout that is not sized and integrated with the house wrap can let water into the wall cavity.
- Gutter stops short of the wall, so the kicked-out water has nowhere to land.
The two-minute ground check
- Walk around the house and find every place a roof edge dies into a wall: porch roofs, garage roofs, first-floor roofs below a second story, dormers.
- At each one, look for a piece that angles out toward the gutter.
- Look at the siding directly below. Stains, swollen boards, soft spots or a vertical paint failure are red flags even if a kickout is present.
- Inside, check the wall under that corner for staining.
You do not need a ladder for this. If you see trouble, a contractor uses a moisture meter and may open a small test area.
The correct fix, and the wrong ones
| Repair | When it fits |
|---|---|
| Install a kickout by removing the lowest siding courses, integrating it with the step flashing and lapping the weather barrier over it | Kickout missing; wall still sound. |
| Replace rotted sheathing and framing, then install the kickout | Rot found once siding is off. |
| Re-side the affected wall section | Damage spreads beyond the corner. |
Wrong fixes: a bead of caulk where the gutter end meets the wall, a site-bent kickout with an open seam, or a kickout stuck onto the face of the siding.
Code and guidance
- Code. The 2024 IRC, section R903.2.1, requires a flashing that diverts water away from where the eave of a sloped roof meets a vertical sidewall. The same section requires flashing at wall and roof intersections generally, and metal flashing at least 0.019 inch thick (No. 26 galvanized sheet).
- DOE Building Science Education. Diverters belong at the eaves of all roof-wall intersections, sized correctly and integrated with the weather barrier; prefabricated units are preferred over site-built ones.
- Siding manufacturers. James Hardie’s HardiePlank installation instructions include a kickout flashing detail among the clearance and flashing details installers must follow.
When to call
Call as soon as you see a stain below a roof-to-wall corner. This is a case where a small part prevents a large repair. Integrity installs roofing and siding, so we can flash and re-side the corner in one visit. For the flashing above the kickout, see roof-to-wall flashing leaks. Water spilling from the gutter at that corner is covered in overflowing gutters. The roof problems guide has the full list. Kickouts are one of several wall leaks; the others are covered in water behind siding, window flashing leaks, deck ledger leaks and, on stucco houses, stucco cracking.
Have a kickout checked
Integrity Roofing and Painting is veteran-owned and family-run since 1990, an Owens Corning Platinum Preferred contractor with 650+ Google reviews. We check every roof-to-wall corner during an inspection and photograph what we find. Colorado Springs area: call (719) 488-2800 or book a free inspection. Denver metro: call (303) 209-0152 or book a free Denver inspection. Austin: call (512) 610-5897 or book a free Austin inspection. We reply the same business day.
Sources: 2024 IRC Chapter 9, section R903.2.1 (UpCodes); U.S. DOE Building Science Education, Kick-out flashing at roof-wall intersections; James Hardie, HardiePlank HZ10 installation instructions.
