What is Roof Kickout Flashing? (Diverting Water and Saving You $1000s)

Roof kickout flashing is a special type of roof flashing designed to protect the edges of a roof from water damage. It’s an important part of any roofing project, but many people don’t know what it is or how it works.

So, what are you waiting for? Read on to find out more!

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What is “roof kickout” flashing?

Roof kickout flashing is a type of flashing that goes where a slanted roof meets a straight wall. Its purpose is to divert rainwater away from the wall and into the gutter system, which helps prevent water damage to the wall and foundation.

The kickout flashing is typically an L-shaped piece of metal that is installed along the edge of the roof and extends up the wall.

The bottom edge of the flashing is angled away from the wall and goes out into the gutter system. This lets water flow into the gutter instead of down the wall.

What would happen if you didn’t use a roof kickout flash?

Without kickout flashing, rainwater can pool where the roof meets the wall. This can damage the wall, the foundation, and the roof decking.

This can lead to rot, mold growth, and structural damage if left unchecked. By putting in kickout flashing, builders and homeowners can protect their buildings from water damage and make sure they will last for a long time.

What are the benefits of using roof kickout

  • Reduces the chance of water damage to the interior of the building
  • Helps to prevent mold and mildew
  • Inexpensive and can save a lot of money in future repairs
  • Increases the life expectancy of the building
  • Diverts water into the gutters
  • Usually welded to create a strong, permanent wand watertight joint
  • Aluminum build is UV ray, ice, discoloration,, mold, and corrosion resistant
  • Prevents major damage to wood framing behind the exterior cladding

Where is kickout flashing needed?

Kickout flashing is needed at the intersection of a sloped roof and a vertical wall, particularly where the roof and wall meet at an angle.

It is often used where the slope of a roof meets a sidewall, chimney, or some other vertical part of a building.

Most of the time, kickout flashing is put on the lower slope of the roof, where water is most likely to run off. It should be put up in a way that keeps water from running down the wall and into the gutter system.

Depending on how the building is built and laid out, the kickout flashing may be in a different place.

When is kickout flashing required?

When a sloped roof meets a vertical wall, building codes usually require kickout flashing, and roofing and construction experts also recommend it.

Both the International Residential Code (IRC) and the International Building Code (IBC) say that kickout flashing must be put in place in certain situations to keep water out.

The IRC says that a kickout flashing must be installed when the roof slope ends at a wall next to the roof. This applies to both new construction and remodeling projects.

The IBC also says that commercial and multifamily buildings with more than one unit must have kickout flashing where the roof meets the wall.

Also, as part of their warranty, many roof manufacturers require kickout flashing to be used. If you don’t install kickout flashing according to what the code says and what the manufacturer says, your warranty could be void and you could be responsible for water damage.

Even if kickout flashing isn’t required by code or a warranty, it’s a good idea to use it when the slope of the roof sends water toward a wall.

This includes areas with heavy rainfall, steep roof slopes, and areas with vulnerable wall construction, such as those with stucco, brick, or other porous materials.

How does roof kickout flashing protect a building envelope?

The kickout flashing’s L-shaped design channels water away from the wall and into the gutter system.

In order to direct water away from the wall and into the gutter, the bottom edge of the flashing is installed at an angle.

This aids in preventing water from penetrating the siding or the wall, which could cause water damage and the growth of mold.

By directing water away from the wall and into the gutter system, kickout flashing helps protect the building envelope from water damage. This helps keep the building from falling apart and saves money on repairs caused by water damage.

How does roof kickout flashing divert water away from a building?

When it rains, water falls onto the roof of a building and flows down the slope of the roof towards the gutter system.

If there is a vertical wall adjacent to the roof, the water can be directed towards the intersection of the roof and the wall. Without kickout flashing, the water can flow over the edge of the roof and enter the wall, potentially causing water damage and mold growth.

The purpose of kickout flashing is to keep water from getting into the wall by directing it away from where the roof meets the wall and into the gutter system.

The flashing is typically installed at the lower end of the roof slope, where water is most likely to accumulate and flow down the wall.

As water runs down the roof, it hits the kickout flashing and is directed away from the wall and into the gutter system. The water flows along the bottom edge of the kickout flashing and into the gutter, where it is carried away from the building and deposited on the ground or goes into a stormwater management system.

How do I install kickout flashing?

Step 1: Measure the length of the area where you will install the kickout flashing.

Use a measuring tape to determine the length needed for the flashing. The flashing should extend a few inches beyond the wall or siding, and it should be long enough to cover the entire roof slope. Add a few extra inches to the length to allow for trimming during the installation process.

Step 2: Cut the flashing to the appropriate length using tin snips or a metal saw.

Use a straight edge or a square to mark the cutting line on the flashing. Then, use the appropriate cutting tool to cut along the line. Wear gloves and eye protection when cutting the flashing to avoid injury.

Step 3: Identify the location where the kickout flashing will be installed.

Look for the point where the roof slope meets the wall or siding. This is typically near the eaves or lower part of the roof. Make sure the area is clean and free of anything that could get in the way of the installation.

Step 4: Take off any siding or roofing materials that might get in the way of putting the kickout flashing in place.

Use a pry bar or hammer to carefully remove any existing materials that may be in the way. Take care not to damage any surrounding materials during this process.

Step 5: Slide the kickout flashing under the shingles or roofing material, and then attach it to the wall using nails or screws.

Place the flashing under the shingles or roofing material to ensure a watertight seal. Then, secure the flashing to the wall using roofing nails or screws. Use a level to ensure that the flashing is straight and flush against the wall. Make sure that the bottom end is securely attached to the gutter or downspout. Use stainless steel or galvanized fasteners to keep the installation from rusting and make sure it will last.

Step 6: Use roofing caulk or sealant to seal the edges of the kickout flashing to keep water out.

Apply a bead of roofing caulk or sealant along the edges of the flashing to seal any gaps and stop water from getting behind the flashing. Use a caulking gun to apply a steady and even bead of sealant. Smooth out the sealant using a caulk smoothing tool or your finger.

Step 7: Put back any roofing or siding that was taken off during the installation.

Use roofing cement or an adhesive to put back any parts of the roof that had to be taken off during the installation process. Make sure that the materials are securely fastened and sealed to prevent water infiltration.

What materials are used for roof kickout flashing?


This is a common material for kickout flashing because it is light, strong, and doesn’t rust. Aluminum is generally considered the most popular material for kickout flashing due to its lightweight, durability, and resistance to corrosion. It is used a lot in the building business and is a popular choice for both home and business roofing projects.


Copper kickout flashing is more expensive, but it is very strong, lasts a long time, and has a unique look.

Galvanized steel

This material is strong and doesn’t cost much, but it may rust more easily than other materials.


Vinyl is a cost-effective option, but it may not be as durable as metal options.


Similar to vinyl, PVC is a plastic option that is lightweight and easy to work with.

How do I know if my roof kickout flashing is installed correctly?

You can test it by pouring water towards the edge of your roof, where it will drain down to the kick-out flashing that you just installed. After doing so, here are a few steps you should take to verify the installation.

  1. Inspect the kickout flashing: The kickout flashing should be installed at an angle to direct water away from the wall and into the gutter. Check that the kickout is securely fastened to the wall and properly sealed to prevent water from seeping in behind it.
  2. Check for water leaks: A properly installed kickout flashing should prevent water from penetrating the building envelope. Check the interior of your home for any signs of water leaks, such as water stains or dampness.
  3. Check for proper alignment: The kickout flashing should be aligned with the shingles or other roofing material to ensure a smooth transition from the roof to the wall. Check for any gaps or misalignments that could allow water to seep in.
  4. Inspect the gutter: The kickout flashing should direct water into the gutter, so check that the gutter is clean and free of debris that could block the flow of water.

How often should I inspect my roof kickout flashing?

At least once a year, preferably before the rainy season or after a big storm, you should check your roof’s kickout flashing.

It is also a good idea to have your roof and flashing inspected by a professional roofing contractor every few years, especially if your roof is more than 10–15 years old.

Regular checks can help find signs of damage or wear and tear, like rust or cracks, that could affect how well the flashing works.

What are the signs of roof kickout flashing needing repair?

  • Water stains on walls or ceilings: If you notice water stains on the interior walls or ceilings of your home, this may be a sign that water is leaking in through damaged or improperly installed kickout flashing.
  • Cracks or rust: Over time, kickout flashing may develop cracks or rust, which can compromise its ability to divert water away from your home. If you notice any visible signs of damage to the flashing, it is important to have it inspected and repaired by a professional.
  • Loose or missing flashing: If the flashing is loose or missing from your roof, this can leave gaps where water can enter and cause damage. It is important to have any loose or missing flashing replaced as soon as possible.
  • Gutter overflow: If your gutters are overflowing during heavy rain, this may be a sign that water is not properly being diverted away from your home. This could be due to a problem with your kickout flashing, among other issues.
  • Mold or mildew: If you notice mold or mildew growing on your interior walls or ceilings, this may be a sign of water damage caused by improperly functioning kickout flashing.

How much does it cost to install kick-out flashing?

The cost of installing kick-out flashing for an average-sized home can range from $200 to $500.

But if the roof is more complicated or the house is in an area where labor and materials are more expensive, the price may be higher.

To get a better idea of how much it will cost to install kick-out flashing on your property, it is best to get a quote from a licensed roofing contractor in your area.

What happens when kickout flashes are missing?

Water damage to walls

Repairing water damage to walls can cost anywhere from a few hundred dollars to several thousand dollars, depending on the extent of the damage.

This can mean replacing the drywall, insulation, and framing, as well as fixing or replacing any broken electrical or plumbing parts.

Mold and mildew growth

The cost of mold remediation can range from a few hundred dollars to tens of thousands of dollars, depending on the severity of the infestation and the size of the affected area.

This cost can include testing for mold, getting rid of it, treating it, and fixing any damaged items.

Structural damage

Depending on how bad the damage is, it can cost anywhere from a few thousand dollars to tens of thousands of dollars to fix structural damage.

This can include things like strengthening the foundation, repairing or replacing damaged framing, and fixing any damage to the roof.

Damage to the roof

Repairing damage to the roof can cost anywhere from a few hundred dollars to several thousand dollars, depending on the type and extent of the damage.

This can include fixing leaks, replacing broken shingles or tiles, and fixing any damage to the flashing.

What’s the difference between step flashing and kick-out flashing?

Step flashing and kick-out flashing are two types of flashing used in roofing to protect against water infiltration.

While they are both designed to direct water away from the building envelope, they are used in different areas of the roof and serve different functions.

Step flashing is a type of flashing that is installed where a sloped roof meets a vertical wall or chimney.

It is a series of small L-shaped pieces of metal, typically made of aluminum or galvanized steel, that are installed underneath each course of shingles and overlap the vertical surface.

The step flashing is built into the shingles and is meant to keep water away from where the roof meets the wall.

Kick-out flashing, on the other hand, is installed at the lower end of a sloped roof where it meets a vertical wall.

It is a piece of metal flashing that is shaped like a small L, with one leg extending up the wall and the other leg extending out over the edge of the roof.

The kick-out flashing’s job is to move water away from the wall and into the gutter system. This keeps water from getting inside the wall and damaging the building envelope.

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Author: Logan

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