Everything You Need To Know About Types of Roof Flashings and How To Install Them

by | Feb 13, 2023 | Roofing

Damaged or incorrectly installed roof flashing is one of the biggest reasons for roof leaks. If you’re starting to see signs of water damage despite having recently repaired or replaced your roof, you most likely have roof flashing issues.

Flashing is a crucial part of any roofing system. A poor installation or repair can significantly compromise overall roof integrity. Without proper roof flashing, the house is more likely to experience leaks, water damage, mold, rust, rotten wood, and even pest problems.

Understanding exactly what roof flashing is, its purpose, and where it is needed plays a big part in maximizing the lifespan of your roof and protecting your home.

What Is Roof Flashing?

Simply put, roof flashing is a weather-proofing method installed on potential water penetration areas in roofing systems. It ensures your roof is watertight. 

The flashing is made of a flat material.  Sheet metal — like stainless steel, galvanized steel, aluminum, or copper — is a popular flashing material. These are widely used due to their durability, though some people use plastic or rubber.

Roof flashing is installed on the most vulnerable parts of your roof to prevent water from seeping through and causing leaks. It covers any openings in the roof and strategically redirects the flow of water away from these potential leak sources. The pieces of flashing overlap each other to ensure the water flows towards the gutters rather than the crevices.

What Parts of the Roof Require Flashing?

Areas that are most susceptible to water damage require roof flashing. In general, these are the parts of your roof that intersect or overlap with a wall, window, or other parts of the roof.

Some critical areas that need roofing flashing around it include:

  • Chimneys
  • Wall sidings
  • Pipe, hood, and other types of vents
  • Skylights
  • Valleys, or the area where two sloped roof edges meet
  • Roof edges, such as eaves

Different Types of Roof Flashings

The concept of roof flashing does not change regardless of where it’s installed. However, different types of flashing work better for certain situations. The kinds of roof flashing generally depend on where or how it is installed. These include the following.

Headwall Flashing

Headwall flashing — also known as apron or base flashing — is installed wherever the roof intersects with vertical junctures or walls. This type of flashing is used to prevent water damage and leaks that stem from vertical-to-horizontal roof intersections

It’s typically installed behind wall sidings and shingles. In cases where the headwall is made of brick, the headwall flashing is paired with an overlapping counterflashing

Step Flashing

Step flashing uses L-shaped pieces of roof metal flashing. It’s typically installed against walls and other roof penetrations, particularly along corners where the roof system intersects with sidewalls. 

Step flashing is always partly visible. Since it’s designed to shed water to the course under it, allowing it to redirect water towards the gutter without the need for sealant, it needs to be extended by at least a couple of inches.


Counterflashing is usually installed alongside other types of metal roof flashing, such as step flashing and headwall flashing. As the name suggests, it goes in a counter direction of the other flashing. 

Counterflashing can go on top, covering the other flashing, or opposite the base flashing. Aside from redirecting water flow, it’s also used to protect the base or step flashing.

Chimney Flashing

Chimney flashing is essentially just counterflashing installed around the chimney base to seal it against any leaks.

For best results, this type of flashing should be installed at the same time that the chimney is being built. If not, then roof flashing installers will need to cut into or grind around an inch deep into the mortar joints of the chimney to install custom roof flashing.

Valley Flashing

Valley flashing is the type of roof flashing used wherever two sloping sides of a roofing system meet or come together — basically forming a valley. When installing this type of roof metal flashing, roofing contractors also install a self-adhering ice and water shield in the middle of the valley for added security.

Gutter Apron Flashing

The gutter apron flashing is specifically installed where the roof and gutter meets. Similar to step flashing, gutter aprons are also L-shaped. 

Gutter aprons are installed along the gutter line and underneath the shingles. Aside from directing the water to flow into the gutters, this flashing also blocks small insects and animals from getting into the attic.

Drip Edge Flashing

Drip edge flashing is similar to gutter aprons; it’s also installed along the gutter line or edges of the roof. The main difference between the two is their shape. Instead of an L-shaped metal sheet, drip edge flashing has a T-shape.

Another difference is where exactly the flashing is installed. Drip edge flashing is installed along the trim of the roof rather than underneath the shingles, essentially hanging directly behind the gutter.

Kickout Flashing

Kickout flashing is installed wherever gutters end against a side wall or at the end of any roof and wall intersection. It’s also referred to as diverter flashing, as it diverts water towards the gutter and away from the exterior cladding.

When Should I Repair or Replace My Roof Flashing?

Like other roof-related repairs and replacements, installing new roof flashing requires intensive labor. As such, the prices can be expensive. The average costs of flashing repairs in the U.S. fall between $200 to $500. Meanwhile, flashing replacements can go up to $300 to $1,500 depending on the state, contractor, flashing material, and other factors.

Thankfully, roof flashing is durable. With correct installation and proper care, it can last for as long as 40 years — barring any extreme weather occurrences. In general, it has the same lifespan as your entire roof, which makes it easier to schedule replacements at the same time.

If your roof flashing is nearing 40 years old, it may be best to get a thorough professional inspection to ensure that everything is still secure and works as intended.

We recommend getting your flashing and roof system inspected twice a year. This helps you catch potential issues early and avoid higher replacement costs. At SWORD Roofing, we offer free professional roof inspections and job estimates to ensure your roof is taken care of properly.

Signs You Need New Roof Flashing

Aside from professional roof inspections, it’s also advantageous to do regular roof self-checks. Below are a few easy-to-spot signs of potential roof flashing issues and roof problems:

  • Corrosion and rust, particularly along the flashing and gutter line
  • Broken or curling shingles
  • Empty patches on the roof due to falling shingles
  • Leaks and water stains along the attic or interior walls
  • Mold and mildew growth, either on the roof or inside

How To Install Roof Flashing

The specifics of installing roof flashing will depend on the type of flashing necessary and the materials of both the flashing and the roof itself.

For instance, flashing is typically installed underneath the roofing material, such as shingles. However, in the case of metal roofs, the flashing is usually installed on top of the roof panels.

Below are the basic steps in installing flashing on shingle roofs:

  • Remove the shingles around the area.
  • Remove old underlayment under the shingles and install a new one.
  • Remove any previous roof flashing.
  • If the roof ends against a sidewall, install the kickout flashing at the bottom first.
  • Start laying out step flashing.
  • Continue laying out the step flashing until it reaches the kickout flashing.
  • Use roofing cement and nails to keep everything in place.
  • Once all the flashing is secure, start putting back the shingles.
  • Layer the shingles on top of the flashing to cover any seams.

Professional Roofing Services for Premium Roof Flashing

Roof flashing repair and replacement is a challenging task. Even after enumerating all the necessary steps for installing new flashing, it’s still difficult to do the job yourself. 

Missing even the smallest of spaces or failure to properly seal even a tiny corner can cause huge and expensive problems over time. As such, it’s best to leave roof flashing installation to the experts for optimum results.

If your roof flashing shows signs of disrepair, or you start to experience leaks and water damage issues after a self-repair job, make sure to consult reliable roofing contractors. Hiring a well-experienced and highly skilled team like SWORD Roofing to install your roof flashing ensures that the job is done correctly on the first try. 

Call Southwest Ohio Roof Defense today at (513) 298-9981 to request a free roof inspection and quick estimate.

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