Roof flashing is material or a formed component that manages water where a roof covering ends or is interrupted. It helps preserve the drainage path and directs water out and down at vulnerable transitions, rather than letting it enter the roof or wall assembly or concentrating runoff on a vulnerable wall.
What roof flashing does
A roof is a drainage system: water should travel over the roof covering and away from the building. Edges, openings, intersections and penetrations interrupt that path. Flashing bridges those transitions and connects the roof’s water-shedding layers to adjacent roof or wall layers so water can drain out instead of behind them. Building Science Corporation describes flashing as necessary wherever a drainage plane is terminated or interrupted, including at roof edges, openings, intersections, control joints and penetrations (Info-303: Common Flashing Details).
The guiding principle is “down and out”: flashing should carry water out over the cladding or drainage plane, without openings that can send it back into the wall. Simply covering a visible seam is not enough if the flashing does not connect to the layers that manage water behind the roof covering or cladding.
Where roof flashing should be installed
Flashing is used where the roof covering terminates, changes direction or is penetrated. The appropriate detail depends on the roof covering and the adjoining wall or other assembly.
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- Exceptional Durability: Are you still worried about roof leaks and grass growth? Our aluminum flashing roll offers long-lasting protection, with a lifespan exceeding 20 years. Unlike standard steel coils that may corrode and cause leaks in a few years, our rust-resistant, anti-corrosion metal flashing ensures your roof and walls stay secure and leak-free for decades.
- Versatile for DIY Projects: Available in various widths (6", 8", 12", 24", 40") and lengths (50ft, 100ft), our aluminum roll is perfect for all your home improvement needs. Whether it’s roofing, roof flashing, or garden projects, these rolls provide the flexibility and strength required for a wide range of DIY applications.
- Lightweight Yet Strong: With a thickness of 0.0118 inches/0.3 mm (26GA), our aluminum flashing combines lightweight properties with high strength, making them easy to handle and install while offering robust protection against the elements.
- Superior Aesthetic Appeal: Not only is our aluminum flashing functional, but it also enhances the visual appeal of your home. The smooth, polished surface adds a clean, modern look to roofs, walls, and other exterior applications, ensuring your property looks its best.
- Outstanding Weather Resistance: Engineered to withstand extreme weather conditions, our roof flashing strips resist bending, warping, or expansion under wind pressure, temperature changes, and humidity. This makes them an ideal choice for both residential and commercial applications, ensuring long-term peace of mind.
- Roof edges and perimeters: At the roof’s termination, flashing helps weatherproof the edge.
- Valleys: Where two roof planes meet, the flashing detail must suit the roof covering and its installation instructions.
- Pitch changes: A change in roof plane interrupts the covering and may require flashing designed for that transition.
- Roof-to-wall junctions: A sloped shingle roof meeting a vertical sidewall typically needs step flashing integrated with the shingles.
- At the bottom of a roof-to-wall run: Kick-out flashing directs concentrated runoff away from the wall rather than letting it pour down the wall surface.
- Roof-to-chimney junctions: Shingle installation instructions specify flashing at chimneys; the exact arrangement depends on the roof and chimney assembly.
- Penetrations, expansion joints and drains: These interruptions and terminations need flashing details appropriate to the roof system.
The 2025 FORTIFIED Home Standard lists edges, valleys, pitch changes, penetrations, expansion joints and drains among flashing locations. Its provisions apply to homes pursuing that designation; local code and project-specific instructions also matter.
How step and kick-out flashing work at a sidewall
Step flashing runs with the shingle courses
At a sloped shingle roof that meets a vertical sidewall, individual step-flashing pieces are interwoven with the shingle courses. Each piece has an upturned leg at the wall and a lower leg over the roof drainage plane. The upturned leg must connect to the wall’s drainage plane, either by being placed behind it or sealed to it; the lower leg sheds water onto the roof. This layered arrangement lets water drain out rather than behind the wall covering.
Rank #2
- 【Package】: includes 1 Pcs 6in x 10ft, 32 Gauge (0.0078"/0.2mm) Thickness roll of aluminum flashing, This provides enough material to complete most small to medium project with ease.
- 【Excellent Quality Material 】: Made of premium ASTM B209 1060 aluminum alloy , this roof flashing ensures outstanding malleability and provides resistance against corrosion or rust, Its sturdy construction ensures durability and reliability.It is designed to withstand all weather conditions and resist corrosion, ensuring that it will last for years to come.
- 【Weatherproof Function】: the aluminum flashing is not easy to bend, deform or expand under wind pressure, temperature and humidity, and has high strength, which can be applied to withstand different weather conditions, such as rain, snow and other bad weather, making it suitable for indoor and outdoor use. And can provide reliable protection and ensure the service life of your project.
- 【Easy Installation】Aluminum flashing roll sheet is easy to install and can be cut to size with a pair of scissors; it can be secured to the surface using nails, screws or tapes, depending on the application.Easy to use and process.
- 【Wide Application】: The aluminum roof flashing is suitable for roofs,doors,windows, kitchens, living rooms, aluminum composite panels, aluminum veneer,aluminum ceilings, trim, siding, flooring,It is compatible with most types of construction materials such as wood, brick, and concrete, making it a versatile item for DIY project.
Owens Corning’s U.S. shingle instructions call for corrosion-resistant 26-gauge metal step flashing at least 8 inches long and 2 inches wider than the expected shingle exposure at vertical sidewalls or chimneys (Owens Corning shingle installation instructions). That dimension is for the cited manufacturer’s product instructions, not a universal specification. Follow the instructions for the specific roof covering and the locally applicable building code.
Kick-out flashing sheds water at the bottom
Where the roof-to-wall junction ends, kick-out flashing turns the runoff away from the wall and out over the cladding. Building Science Corporation explains that kick-out flashing is used at the bottom edge of a roof-to-wall intersection, where the roof ends and the wall continues (BSP-020: Water Management Details for Residential Buildings). It is a distinct part of the drainage detail: step flashing handles the run along the wall; kick-out flashing directs water clear of the wall at the end.
Rank #3
- Outstanding Durability:With a thickness of 0.0118 inches/0.3 mm,our aluminum flashing combines lightweight properties with high strength,making them easy to install while offering robust protection against the elements.
- Product Size:The aluminum roll measures approximately 50 feet long and 12 inches wide,provide the flexibility and strength required for a wide range of your roof flashing, or garden improvement projects.
- Good Material:Our metal flashing is made of aluminum, strong enough to withstand harsh outdoor weather conditions, such as rain, wind, and sun; It is also rust and corrosion resistant, sever you a long time.
- Package Including:you will get a roll of aluminum roll flashing,a pair of cut resistant work gloves,a work scissors,enough for satisfying your installation needs.
- Wide Application:The aluminum flashing is suitable for many different construction projects,such as aluminum veneer, aluminum ceilings,roof flashing, and more;It is compatible with most types of building materials such as wood,brick,and concrete,making it a versatile item for home improvement.
How masonry veneer changes the detail
Brick and stone veneer usually have a water-control layer behind the masonry. Surface-mounted step flashing alone may not connect to that layer, so water behind the veneer can remain trapped or reach the wall assembly instead of draining to the roof. Building Science Corporation describes through-wall flashing as a way to carry water from behind the veneer to the exterior. The detail must be designed for the specific veneer and wall assembly (BSP-020: Water Management Details for Residential Buildings).
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Choose details for the roof and the applicable requirements
Flashing is not one interchangeable piece used everywhere. The right detail depends on the transition being protected, how the roof covering and wall drainage plane connect, and the materials and exposure of the assembly. Before specifying or replacing flashing, check the roof-covering manufacturer’s instructions and local code.
Quick Recap
Best Value
- What You Will Receive: you will get 20 pieces of roof flashing, about 5 x 7 inches/ 12.7 x 17.7 cm, enough for you to use, and you can trim them into the size you want, convenient and easy to use
- Reliable Material: the waterproof roof flashing for roofs is made of quality aluminum material, no smell, strong and reliable, but pay attention to aluminum products, the surface will turn black after soaking in rain for a long time, you need to replace it in time, but it does not affect the use
- Effective Features: the aluminum flashing can help you to help add an extra layer of weatherproof protection to your roof, these flashings can be applied to help weatherproof chimneys, skylights and around skylights, effective and safe
- Ease of Installation: the aluminum sheet metal is relatively easy to install and can be cut to size using a pair of tin snips; It can be attached to surfaces using nails, screws, or adhesive tape, depending on the application
- Multi Scenario Use: not only the metal flashing as a weatherproof area for roofs around chimneys or skylights, but also as an accessory to prevent mouse drilling and bird repellents, and more
Rank #4
- Exceptional Durability: Are you still worried about roof leaks and grass growth? Our aluminum flashing roll offers long-lasting protection, with a lifespan exceeding 20 years. Unlike standard steel coils that may corrode and cause leaks in a few years, our rust-resistant, anti-corrosion metal flashing ensures your roof and walls stay secure and leak-free for decades.
- Versatile for DIY Projects: Available in various widths (6", 8", 12", 24", 40") and lengths (50ft, 100ft), our aluminum roll is perfect for all your home improvement needs. Whether it’s roofing, roof flashing, or garden projects, these rolls provide the flexibility and strength required for a wide range of DIY applications.
- Lightweight Yet Strong: With a thickness of 0.0118 inches/0.3 mm (26GA), our aluminum flashing combines lightweight properties with high strength, making them easy to handle and install while offering robust protection against the elements.
- Superior Aesthetic Appeal: Not only is our aluminum flashing functional, but it also enhances the visual appeal of your home. The smooth, polished surface adds a clean, modern look to roofs, walls, and other exterior applications, ensuring your property looks its best.
- Outstanding Weather Resistance: Engineered to withstand extreme weather conditions, our roof flashing strips resist bending, warping, or expansion under wind pressure, temperature changes, and humidity. This makes them an ideal choice for both residential and commercial applications, ensuring long-term peace of mind.
- Match the flashing detail to the location: edge, valley, pitch change, wall, chimney or penetration.
- Make sure the detail connects the relevant drainage layers and directs water out and down.
- For masonry veneer, account for drainage behind the veneer and the through-wall connection.
- Check the requirements of any program or designation governing the project. Under the 2025 FORTIFIED Home Standard, new flashing and fasteners must be corrosion-resistant metal, and existing flashing must be removed and discarded when reroofing under the standard.
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