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Guide to Roof Flashing (Types and Installation)

January 03, 2023
Common Flashing Details

There is more to your roof than meets the eye. Many details exist on a roof; regardless if it is a commercial or residential structure. Those details are referred to as flashings. All roofing systems require flashings to weatherproof any area where a penetration or change in the structure occurs. Flashing is incredibly important as they defend your property from leaks and prevent damage to both the interior and exterior. The most common flashing details include (but are not limited to): rakes, eaves, pipes, vents, walls, windows, skylights, and chimneys. Flashing problems occur when they are not installed to proper detail, have defects (damage), or are reused. Now that we know the importance of flashing, let’s look at the most common details.

Guide to Roof Flashing (Types and Installation)

Chimney Flashing Details

Chimneys mostly consist of counter flashings. Counter flashings are custom fabricated metal that is “L” shaped. The counter flashings go onto the chimney and roof deck (roofing removed) with the seam of the “L” nestled where the two areas meet. Dependent upon the chimney type (siding or exposed brick), you would then install a step-flashing (brick) or Ice & Moisture Guard (sided chimney). Chimneys may also have a bladder detail at the back where a triangular shape sheds water away from the back of the chimney. The area would similarly be reworked with a rubber bladder to ensure waterproofing. Below you will see before, in progress and after photos of two types of chimney flashing repairs.

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Sidewall & Headwall Flashing Details

Sidewall and headwall flashings are installed where the front (headwall) and side (sidewall) walls intersect with the roofing system. The flashing goes behind the siding and then runs onto the roof deck. These flashings are of similar “L” shape flashing and will protect against infiltration at the interior and exterior. Now if the home or business is brick, we would counter that flashing over the headwall flashing so water continuously sheds. Below you will see examples of headwall flashings (before, during, and after) and sidewall flashings.

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Skylights have both visible and hidden flashing on all sides of the skylight. Flashings are designed to shed water without relying on sealants that can break down over time and cause damage to your roof. Your skylight is either deck mounted (straight to the roof deck) or curb-mounted (box built up above the roof line). The areas are moisture-wrapped and then metal flashings are installed. On a shingle roof, you will see metals at either the top, bottom, or sides of the skylight – depending on the roof’s pitch, shingle material, etc. Below you will see an example of an improperly installed skylight (before, during, and after). This skylight “lasted” 5-6 years before leaking. As you can see from the pictures, the damage was far worse than one would anticipate.

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Pipe & Vent Flashings

Penetrations and vents are found on all roofing systems. At the base of each type of penetration, there is a layer of metal and/or rubber. Most flashing kits are a combination of both materials. When installed, you will see partial exposure from the roofing system of these flashings. Although these flashings are a protector, rubber gaskets that circle the penetration will crack and weather over time. You can seal these gaskets with caulking or replace the pipe boot itself. At both pipes and vents, it is imperative that they are flashed according to roofing system specifications. Below are examples of improper and proper flashings (before and after).

Pipe & Vent Flashings Pipe & Vent FlashingsPipe & Vent FlashingsPipe & Vent Flashings

Window Flashings

Windows are more intricate than what meets the eye. Aside from the window itself, it must be framed into the home properly, wrapped (insulated), flashed, and sided. Deconstructed, windows have different types of flashing on each side as follows: cap and head flashing (top of the window), jamb (side) flashings, and sill (bottom) flashing. Flashing helps prevent any moisture (condensation, rain, snow) from entering the small gaps in the siding. As one may imagine by the time you know there is a problem, it has been occurring “behind the scenes” for a while.

Window Flashings Window Flashings Window Flashings

Experienced Omaha Roofing Company

Big or small, we can do it all. Here at McKinnis, we pay attention to details. We understand that the smallest of details can cause the biggest of headaches. Whether you have evidence of moisture, are starting from scratch, or are looking at getting a remodel done, we will assess all components of your project to ensure the highest quality of workmanship. Roof flashing details are one of the most underrated building enclosure components, however, they are one of the top priorities for McKinnis. We put our name on it so you can count on it!


If you are in need of roofing, windows, siding, or gutter work, give us a call today at 402-426-2644, visit our website at or fill out our contact form. Our roofing and exterior experts are highly trained and always ready to help!