How to Install Kickout Flashing Where a Roof Edge Meets a Wall
A small angled piece of metal that stops the most destructive leak a house can have: water running behind the wall, unseen.
- Advanced
- 1 to 2 hours
- Updated
The short answer
A kickout flashing is an angled piece of metal installed at the bottom end of a sidewall, where the roof edge meets the wall. It catches the water coming down the step flashing and diverts it into the gutter, not behind the siding. Install it over the drip edge and starter, tight to the wall, with a rise of at least 4 inches and about a 110 degree kick away from the wall.
Step flashing carries water down along a wall. At the bottom of that wall, the roof ends at the eave and the last piece of step flashing hands that water off. Without help, the water runs off the end of the flashing and straight down the face of the wall or behind the siding at the roof edge. A kickout flashing is a formed piece of metal that catches that water and throws it out into the gutter.
It is small, cheap, and often missing. Kickouts are among the leading causes of hidden rot in wood-frame houses, because the water goes behind the cladding where no one sees it. Sheathing, framing and insulation decay from the outside in, and the first sign is often a soft spot when someone leans on the wall.
This guide covers new installation and the retrofit on an existing roof. It works together with step flashing above it and drip edge and gutters below.
Tools
- Tin snips (straight cut)
- Hand seamer
- Flat bar for lifting siding
- Hook blade utility knife
- Caulk gun
- Tape measure
- Hammer or nailer
Materials
- Pre-formed kickout flashing or 26 gauge sheet metal
- Ice and water shield
- Step flashing for the lowest courses
- Roofing nails, 1-1/4 inch
- Sealant rated for metal and the wall cladding
- Flashing tape for the wall barrier
Safety first
- Kickouts sit at the eave, where the roof edge is the fall line. Tie off. WorkSafeBC requires fall protection at 3 metres (about 10 feet) and wherever a fall could cause serious injury.
- Leaning over a gutter to reach the bottom of a wall puts your weight on the edge. Use a proper ladder set-up or work from the roof side, never from a gutter.
- If the wall has been wet a long time, expect soft sheathing and possible mould. Wear a respirator when opening up rotted areas.
Step by Step
Step 1: Find where the wall meets the eave
A kickout goes at the lowest end of any roof to wall junction where the roof edge continues past the wall: dormer cheeks, house additions, garage to house walls. Inspect from the ground with binoculars. Look for dark staining, peeling paint or rot on the wall just above the roof line, which are signs a kickout is missing or failed.
Step 2: Open the wall and inspect before installing
Pry the siding gently with a flat bar and lift the bottom two or three courses, or cut the siding nails if needed. Probe the sheathing and the framing with a screwdriver. If you find soft or black wood, the kickout will stop future water but not repair the damage. Replace rotted sheathing first.
Check the building paper or housewrap. It should be intact and in a shingled arrangement. Patch it with flashing tape if it is torn.
Watch out: If the rot reaches the wall framing or rim joist, stop and call a professional. Structural repair should come before any flashing work.
Step 3: Prepare the eave: drip edge, membrane and starter
The kickout goes over the eave drip edge, the ice and water shield and the starter strip, and under the first piece of step flashing above it. If the eave protection is missing or damaged at that corner, redo it first so the lap order is correct. See the lapping rule.
Step 4: Size and form the kickout
A typical kickout is 4 to 5 inches tall against the wall and angled away from it by roughly 110 degrees, with a bottom face that reaches about 2 inches beyond the edge of the roof into the gutter, or sits over the gutter edge. The bottom flange laps over the starter and drip edge. The top of the diverter laps under the first full piece of step flashing above.
Preformed metal kickouts are cheap and consistent. If you bend your own, soft seams and sharp corners are common. Use a hand seamer or brake and keep pieces symmetrical.
Step 5: Install the kickout tight to the wall
The diverter should sit tight to the sheathing with no gap behind it. A gap is where water sneaks behind the flashing. Fasten the bottom flange with one or two roofing nails in the lower corners of the flange, never through the vertical face or the wall leg. Seal the joint between the kickout and the wall with a bead of flexible sealant only as a secondary measure.
Step 6: Lap the first step flashing over the kickout
Water from the step flashing must run onto the top of the kickout, then into the gutter. That is the lapping rule again. If the kickout is installed over the step flashing instead, the joint funnels water behind both. See step flashing.
Step 7: Close the wall over the kickout
Lap the housewrap or building paper over the top of the kickout's back edge and tape the seams. Reinstall the siding with the manufacturer's clearance to the roof, typically between 1/2 inch and 2 inches. The siding bottom edge and the kickout's vertical edge should not touch. See flashing by cladding type.
Step 8: Test it with water
With a hose from above, watch the discharge. It should land in the gutter and not spray back against the wall. If it splashes onto the siding, the kickout is too short or too straight and needs a longer or more angled diverter.
Retrofitting a Kickout on an Existing Roof
You do not have to replace the roof to add a kickout. Lift the lowest siding course, cut the last shingle back, slide a kickout under the lowest step flashing and over the starter, and replace the shingles and siding. The most common obstacle is that the existing bottom flashing is not step flashing at all but a short piece of rolled metal that is nailed to the wall. In that case replace the bottom two or three pieces with proper step flashing and add the kickout.
Signs a Kickout Is Missing or Failed
- Dark streaks running down the siding below the end of the roof line.
- Paint peeling or bubbling on the wall just above the eave.
- Soft spots or swelling in the siding or trim at the bottom of the wall.
- Water stains on an interior ceiling or wall near the corner where the roof meets the wall.
- A gutter that is dry at the very end of a wall run while the wall below is wet.
Fraser Valley Notes
A house in the Fraser Valley typically sees many months of steady rain, and wind drives it sideways against walls. That constant moisture feeds rot behind a wall quickly, and moss and fir needles in a gutter make it worse by backing water up under the kickout. Keep the gutter below the kickout clear and check it each fall.
Common Mistakes
- Leaving the kickout out altogether. Every drop of water from the wall run lands against the cladding and rots the wall in silence.
- A kickout that is too short or too flat, so water splashes back against the wall or misses the gutter.
- Installing the kickout over the step flashing instead of under it, which directs water behind both.
- Gaps between the kickout and the wall where water sneaks behind. The diverter must sit tight to sheathing.
- Caulking a flat piece of metal and calling it a kickout. Without the angle and height it does not divert anything.
- Ignoring the gutter below. A kickout that discharges onto a clogged or missing gutter just soaks the wall from below.
When to Call a Professional
If lifting the siding reveals black or soft sheathing, or you find a kickout was never installed on a wall that has been wet for years, bring in a roofer or a contractor who can assess framing. Rot at a wall end often goes deeper than it looks.
Kickouts on second storey walls and over steep roofs are a fall risk in their own right. If you cannot reach the spot safely with anchored fall protection, do not attempt it.
Fraser Roofing does free roof inspections across the Fraser Valley, from Hope to Abbotsford. See our Roof Repair service or the towns we cover.
How to Install Kickout Flashing: Questions
What is a kickout flashing?
A kickout flashing, also called a diverter, is an angled piece of metal installed at the bottom end of a roof to wall junction. It catches the water that has run down the step flashing and kicks it out into the gutter, instead of letting it run behind the siding at the roof edge. It is small but it prevents one of the most common causes of wall rot.
What happens if there is no kickout flashing?
Water running down the wall and step flashing dumps straight against the cladding at the eave. It soaks behind the siding, then wicks into the sheathing and framing. The damage is often invisible for years, with mould and rot developing inside the wall. By the time staining or a soft spot appears outside, the damage is typically extensive.
How big should a kickout flashing be?
Commonly about 4 to 5 inches tall along the wall and 4 to 6 inches long, angled away from the wall at roughly 110 degrees so water is thrown into the gutter. The bottom flange laps over the starter and drip edge. Sizes vary by product, so follow the flashing manufacturer's instructions and make sure the discharge actually lands in the gutter.
Can you add a kickout flashing to an existing roof?
Yes. Lift the lowest siding course, trim back the last shingle, slide the kickout under the lowest step flashing and over the drip edge and starter, then restore the shingle and siding. If the old bottom flashing is a flat strip and not proper step flashing, replace it at the same time. Check the wall sheathing for rot when the siding is open.
Where does a kickout flashing go?
It goes at the very bottom of a sidewall where the wall meets the roof edge, directly in line with the gutter. It sits over the drip edge and starter course, tight to the wall sheathing, and under the first full piece of step flashing above. Water then travels from step flashing to kickout to gutter without ever touching the wall.
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This guide is general education. Always follow the product manufacturer's installation instructions, the BC Building Code and WorkSafeBC requirements, which take priority over anything written here.
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