What Is Kickout Flashing?

What kickout flashing is

Picture a one-story garage roof that runs along the wall of a two-story house. Where the roof slope meets the wall, a row of step flashing pieces keeps water out of the joint. That water flows down the roof along the wall until it reaches the eave, the low edge of the roof.

At the eave, the roof stops. The wall does not. It keeps going down past the gutter to the ground.

All the water that ran along the joint now reaches the end of the line.

If nothing turns it, it runs straight down the face of the wall right where the siding meets the roof edge.

A kickout flashing is the part that turns it. It is a small piece shaped like a short channel with a bent nose.

It sits on the roof at that last corner and points out toward the gutter.

The U.S. Department of Energy says, "Kick-out flashing directs rainwater into rain gutters where it can be carried away from the structure" ².

The name comes from what it does. It kicks the water out, away from the wall.

How a kickout keeps water out of the wall

Water on a roof follows the easiest path. Along a sidewall, the step flashing gathers it into a narrow stream right beside the wall. On a big storm that stream can carry a lot of water, because it collects everything that fell on the wall above and on the roof beside it.

When that stream reaches the eave, it has two choices. It can fall into the gutter, or it can cling to the wall and run down behind the end of the gutter.

Water tends to cling to surfaces, so without help a good share runs down the wall. There it finds the seams in the siding, the nail holes and the top edge of any trim, and gets inside.

The kickout gives the water a wall of its own to run against. Its upright side stops the water from reaching the house wall, and its angled end points the stream out over the gutter.

The Building America guide says to install it "at the end of a roof-wall intersection to divert water away from the wall and into gutters" ³.

It only works if it is tied into the wall's water barrier. DOE says kickouts "must be right sized and integrated with the water-resistant barrier, or housewrap" ².

The housewrap or building paper on the wall should lap over the kickout's upper edge, just as it laps over the step flashing, so water on the wrap lands on the flashing and not behind it.

Kinds of kickout flashing

DOE and the Building America guide sort kickouts into two groups: made in a factory, or bent on site ^{2 3}.

The last row is the most common thing a home inspector finds. Whether it meets the code depends on whether it actually diverts the water, which the local inspector decides.

Worked example: how much water reaches one corner

A two-story wall rises 10 feet above a garage roof. The garage roof runs 16 feet up the slope beside that wall. In a 1-inch rain, here is roughly how much water reaches the bottom corner from the wall face alone (illustrative math, not a design number):

Add the roof strip next to the wall, and one storm can send dozens of gallons past a single corner. That is why DOE says the kickout must be "large enough to handle expected stormwater flows" ³. The point of the example is scale: a missing kickout is not a few drops.

Where you need a kickout on a house

You need one anywhere a sloped roof edge ends against a wall that continues down past it. DOE says kickouts "should be installed at the eaves of all roof-wall intersections" ². Common spots include:

A garage or porch roof that runs along the side of a taller house. A dormer roof whose eave ends against the main roof's wall. A lower roof on an addition that meets the original house. A shed roof over a bay window where the slope runs along a side wall.

Look for the place where a gutter ends at a wall. If the roof slope runs up beside that wall, the corner should have a kickout.

The Building America guide adds that "the end of the gutter should not touch the intersecting wall; there should be a small gap to allow free drainage down the wall" ³.

A gutter jammed tight against the siding traps water and debris right at the corner.

You do not need one where the roof meets a wall head-on across the slope. That spot uses apron flashing. And you do not need one where the roof edge and the wall end together at the same corner, because there is no wall below for the water to run down.

Why a missing kickout causes hidden wall rot

This is the main reason the part matters. The Building America guide says missing kickouts have caused "thousands of dollars worth of damage for homeowners" and lists "significant damage to wall sheathing, framing, insulation, and mold inside the wall cavities" ³.

The damage hides because it happens behind the siding. Water that runs down the wall at the corner gets behind the siding and soaks the sheathing, the wood panels nailed to the studs.

It may never drip into a room. Instead it wets the same few square feet of wall in every rain, and wood that stays wet that often starts to rot.

By the time you see a sign, the damage can be deep.

Typical signs include a stain or streak running down the siding below the corner, paint that peels or bubbles there, soft or swollen trim, a bulge in the siding, or a musty smell inside the wall near that corner.

Stucco and some sidings can look fine on the surface while the wall behind them is wet. A roof inspection that looks at sidewalls is the way to catch it early.

Benefits of kickout flashing

• Sends the stream of water from the roof-to-wall joint into the gutter instead of down the wall
• Protects the sheathing, framing and insulation in the wall below the corner ³
• Is a small part, so it adds little to a new roof but protects a large part of the wall
• Meets the 2021 IRC rule in R903.2.1, which inspectors can check ¹
• Works with step flashing and housewrap so the whole roof-to-wall joint sheds water in layers

What a kickout cannot do

• It cannot fix a wall that is already rotten. Damaged wood must be cut out and replaced first.
• It cannot work if the housewrap is tucked behind it. DOE says it must be integrated with the water barrier ².
• It cannot save a corner where the gutter is clogged or too small. DOE notes gutters can overflow and stream down walls in big storms ².
• It cannot make up for missing or bad step flashing above it.
• A small, site-bent piece may not carry the flow of a big storm ^{2 3}.
• It is hard to add cleanly to an old wall. The lower siding usually has to come off.

What drives the cost of adding a kickout

• New roof or retrofit. On a new roof or reroof, the kickout goes in as the shingles go on, so it adds little. Added later, it means opening the wall.
• Siding removal. The Building America retrofit guide removes enough siding to expose the housewrap above the joint ⁴. Vinyl often comes off and goes back; fiber cement, wood or stucco can mean repair work.
• Hidden damage. If the wall is wet or soft behind the corner, sheathing and framing repair is usually the biggest cost.
• Kind of kickout. A molded plastic part, a welded metal part and a soldered metal unit differ in price and labor.
• Gutter work. A gutter jammed against the wall may need to be shortened or reset with a gap ³.
• For a full-roof budget, use our roof cost calculator or the roofing cost guide.

How a crew installs a kickout

This is what you should see on a reroof or a retrofit, from the DOE and Building America guides. It is not a do-it-yourself guide. Roof work is a fall risk, and a licensed roofer should do it.

1. The crew removes the roofing at the corner and enough siding above it to expose the housewrap or building paper ⁴.
2. They inspect the wall at the eave for rot from past leaks and repair it as needed ⁴.
3. Underlayment and any self-adhering membrane go on the roof deck at the corner ⁴.
4. The kickout goes in first, at the very bottom of the run. It is fastened and sealed to the roof deck and starter strip, not the sidewall ³.
5. Step flashing goes in above it, one piece per shingle row, each piece lapping the one below ⁴.
6. The housewrap is lapped down over the kickout and the step flashing, and the siding goes back on ⁴.
7. The gutter end is set with a small gap from the wall so water can drain freely ³.

How to check a kickout as the roof ages

• Stand on the ground and find each place a gutter ends at a wall. There should be a kickout at every one.
• The kickout should point out over the gutter, not down at the gutter end or back at the wall.
• The gutter at that corner should be clear of leaves. A clogged gutter sends water back toward the wall.
• The siding just below the corner should be clean and dry, with no stains, streaks, peeling paint or bulges.
• Watch the corner during a hard rain from a window or the ground. Water should land in the gutter.
• From inside, check the wall and ceiling near that corner for stains or soft drywall.

Common kickout mistakes

• No kickout at all. Often found on older houses and on roofs where the code rule was not enforced.
• Too small. A bent-out last step piece may turn a little water but not a storm's worth ².
• Leaky seams. Site-made pieces can have open seams that let water through ².
• Wrap behind it. If the housewrap does not lap over the kickout, water on the wrap runs behind it ².
• Nailed to the wall. The guide says fasten it to the deck and starter strip, not the sidewall ³.
• Gutter jammed against the wall. The guide calls for a small gap ³.
• Caulk instead of a part. A bead of sealant at the corner is not a diverter.

What the code requires

These rules come from the 2021 International Residential Code, Chapter 9, as adopted in Maryland and read verbatim ¹. States and cities adopt the IRC on their own schedule and can amend it.

Note the code does not say "kickout" or give a size or shape. It sets the job: divert the water away from that spot. The product and the size come from the maker's instructions and the inspector's judgment.

Sources: [1]

Kickout flashing vs related flashing

Common misconceptions

Myth A gutter at the corner does the same job.

Reality The gutter catches water that falls into it. The kickout is what makes the water at the wall fall into it instead of running down behind the gutter end.

Myth Bending the last piece of step flashing out is enough.

Reality It may help a little, but DOE warns site-made pieces can be undersized and leak at the seams ².

Myth No stain means no problem.

Reality The wetting happens behind the siding. A wall can be rotting while the outside looks fine.

Myth Caulk at the corner will seal it.

Reality Sealant is not a diverter. It cracks and still leaves the water running down the wall.

Myth Only new houses need one.

Reality The IRC rule applies to new work, but an older house without one gets the same water at the same corner. It is commonly added at a reroof.

Local code and kickouts

The kickout sentence quoted here is from the 2021 IRC as adopted in Maryland ¹.

Your state or city may use a different edition or amend it, and an older house may have been built under a code that never asked for a kickout.

That is one reason home inspectors find so many corners without one.

A reroof is usually inspected under the code your building department uses today, so ask your roofer which edition applies and whether the inspector checks roof-to-wall corners.

Rainy and windy climates put more water on walls, and houses with stucco or wood siding tend to show the damage later. Your building department, not this page, sets the local rule.

What to ask your roofer about kickouts

• How many roof-to-wall corners does my house have, and does each one have a kickout now?
• Will you add or replace a kickout at every one as part of the job?
• What kind will you use: molded plastic, welded metal or something bent on site?
• Will the housewrap lap over the kickout, and who puts the siding back?
• If you find soft or wet wood at the corner, how will you price the repair?
• Will you leave a gap between the gutter end and the wall?

Keep going

• All roof flashingEvery flashing type in one guide
• Roof repairFixing leaks at walls and flashing
• Gutter servicesThe gutter end at the corner matters too
• Repair or replaceDecide if a wall leak means a new roof

Related terms

Step Flashing

Step flashing is a set of small, L-shaped pieces of metal, one for each row of shingles, woven into the roof where a sloped roof runs up beside a wall, a dormer or a chimney side, so water on the roof is sent back onto the shingles and away from the wall.

Roof Flashing

Roof flashing is thin, water-shedding material, usually bent metal, installed at the joints of a roof where shingles alone cannot keep water out: along walls, around chimneys and pipes, in valleys and at the roof edges.

Counterflashing

Metal flashing set into or over a wall or chimney that laps down over the base or step flashing, so water cannot get behind it.

Drip Edge

Drip edge is a strip of bent metal flashing installed along a roof's eaves and rake edges that carries water off the edge of the roof and away from the fascia and the deck beneath.

Roof Leak

Water getting past the roof covering into the deck, attic or house. Most leaks start at flashing, penetrations or damaged shingles, not open field.

Roof Rot

Decay in the wooden deck, fascia or framing after long exposure to moisture. Rotten deck must be replaced before new roofing goes on.

Chimney Flashing

Chimney flashing is the set of metal pieces that seal the joint where a chimney passes through a roof: an apron on the downhill side, step flashing up both sides, a cricket or back pan on the uphill side, and counterflashing set into the masonry that laps over all of them.

Reroofing

Reroofing is the work of putting a new roof covering on a house that already has one, either by tearing the old covering off down to the deck (a replacement) or by laying the new covering over the old one (a recover, often called an overlay).

Also referenced from: Roof Flashing, Step Flashing, Chimney Flashing