General RoofingRoof Flashing 101

March 2, 2022by American Roofing

Everything you need to know about replacing roof flashing on your property.

Getting a new roof can be an exciting, yet nerve racking process. You might be hearing terms you’re unfamiliar with and want to know more about; one of those terms being roof flashing. This material is crucial in the replacement process, and we’re here to help educate our clients on all things roofing! Here are a few points you should know when it comes to roof flashing:

What is Roof Flashing?

Roof flashing is a thin metal material that professional roofing contractors use to keep water out of your home wherever the roof plane meets a wall. This kind of material is installed around different features of the roof like skylights, vents or chimneys to prevent areas that could potentially lead to leaks. Roof flashing is a must-have investment when having your roof replaced so it’s important that property owners know just what goes into the process.

Are There Different Types?

When it comes to roof flashing, it’s important to be aware that there are multiple options available depending on what your roofing project entails. Aluminum, copper and steel are the most common materials used. Below are the three most common kinds of roof flashing used in the installation process, each one suitable for different parts of your roof.

  • Counter-flashing: This type of roof flashing is mostly seen on chimneys and includes two pieces, base flashing and counter-flashing. One sits around the bottom of the chimney while the other is embedded into the framework of the chimney. Counter-flashing prevents water entry and always involves a second piece.


  • Step flashing: Step-flashing is best used where the roof face meets another wall. In order for water not to slip past the shingles into your property, step-flashing is there to ensure that the water goes directly to the gutter. This kind of flashing is also installed in steps between the shingles.


  • Valley flashing: This flashing style is used to protect an open valley on a roof, using metal flashing for protection. This flashing is usually left exposed, so the roof has lines of metal that run down the valley. Valley flashing protects the middle section where two roof sections come together, and it directs any rainwater away from the roof.


How Is Roof Flashing Installed?

The installation process of roof flashing should always be done by a professional, like our contractors at American Roofing & Waterproofing. How you install roof flashing will depend on which type is being used, but the process of every installation is similar. Valley flashing is the most important kind of flashing because the valleys in your roof risk leaks and erosion if not properly installed. Here’s how it’s done:

Step 1: The first piece of flashing is centered down in the valley starting at the base.

Step 2: The roof valley flashing is then nailed down at the edges to secure it in place, moving up the valley and installing any additional roof flashing.

Step 3: Chalk lines are placed to help guide you as any shingles are installed along the valleys.

Step 4: Roof shingles are installed on either roof face, and then laid down over the valley. Edges are cut to the chalk line.

Step 5: Each valley shingle is nailed down at least two inches back from the chalk line.

Step 7:  The installation is complete by installing the valley shingles and driving in each shingle into three inches of asphalt plastic cement.

We recommend you leave roof flashing installation to the professionals. It is a complex process and your safety and your roof’s quality is our main priority. If you’re in the market for a roof replacement, American Roofing & Waterproofing is your trusted Arizona contractor. We go over the top!


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