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  • Writer's pictureRainy Day Exteriors

Roof Flashing | All you Need to Know

The roof of your home in Gig Harbor, Tacoma, Silverdale, or Port Orchard is made up of many different components – not just shingles and tar paper. And flashing is a crucial component.

Flashing is a piece of metal used to prevent water from seeping into areas of the roof where there is an interruption with the roofing materials, like chimneys, vent pipes, or the perimeter of the roof. Flashing prevents leaks and protects the deck (the first layer of roofing) and underlayment.

Flashing is so important because it is used at several places on your roof and is often the source of leaks.

So, let's learn a little more about flashing.

What’s it Made of?

Roof flashing is made from several different types of materials including aluminum, copper, and steel.


Aluminum flashing is easy to form and is lightweight, but it must be coated when used with concrete and masonry, as plain aluminum reacts and degrades when it touches alkaline surfaces. It is also coated in coastal regions (like the PNW) to prevent corrosion.


Copper roof flashing is a beautiful material that is also easy to work with. It’s incredibly durable and has a long life, but it does discolor into a patina. If you choose this material, just make sure you’re okay with that aesthetic.


Because it is durable and easy to work with, steel is one of the most popular materials used for flashing. Galvanized steel is also corrosion resistant.

When working with your roofing contractor to find the best material for you, just make sure the materials meet the building code. When working with Rainy Day Exteriors, we will make sure your choice matches all the requirements.

Types of Flashing

Continuous Flashing

What is it? Continuous flashing is also known as “apron flashing,” continuous flashing is a long, continuous piece of metal that carries water down to the shingles below. Long pieces of continuous flashing will have trouble flexing as the home expands and contracts in the changing seasons. If left as is, it could break or warp and fail to keep water out. Therefore, long pieces have built-in expansion joints so they can move with the home.

When do you use it? Continuous flashing should be used where a sloped roof meets a vertical wall and forms a horizontal line, like, for example, at a dormer wall.

Base Flashing

What is it? Base flashing is used at any joint between the roofing surface and a vertical surface such as a wall or chimney. It helps prevent water from leaking onto the roof deck.

When do you use it? Base flashing is used at chimneys, which require two pieces of flashing to ensure that rain always meets a flashing surface that forces it downwards. It is notoriously tough to install flashing around a chimney, so roofers have learned to include added protection.

Counter Flashing

What is it? Counter flashing is placed opposite to base flashing, or above base flashing.

When do you use it? Counterflashing completes the two-part system needed at tricky connections like chimneys.

Step Flashing

What is it? Step flashing a rectangle piece of flashing bent at 90 degrees at the center. Multiple pieces are installed in layers with shingles (looking much like a step) to ensure water flows away from the wall.

When do you use it? It is used for roof-to-wall flashing. Multiple pieces of the flashing will be installed in layers with shingles to ensure the water flows away from the wall.

Kickout Flashing

What is it? Kickout flashing directs water away from the wall and into the gutter.

When do you use it? Roofing professionals need something to bridge the gap between where step flashing ends and the gutter begins.

Skylight Flashing

What is it? While some skylight manufacturers include flashing in their products, sometimes roofing professionals have to create it or purchase it separately.

When do you use it? You’ve probably already guessed this, and yes, it’s used around an existing skylight.

Valley flashing

What is it? Valley flashing is often left exposed (not covered with shingles) metal flashing along any valley in your roofline. They direct water down and away from your roof.

When do you use it? They are used on the open valleys of your roof and are invaluable when it comes to directing water away from your roof. Because valleys are low points on your roof, you want to make sure your valley flashing is in tip-top shape.

Drip edges

What is it? The edge of the roof has thin metal flashing that helps water drip off the roof without damaging the home or causing a leak.

When do you use it? You used these “L” shaped pieces of flashing at the edge of your roof.

Flashing is such an important part of your roof system, so knowing all you can about this very important piece is a good idea.

If you’re ready to start the process of getting a new roof, please contact us today!

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