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How To Flash A Roof

Understanding The Difference Between L

How to Install Flashing on a Roof | Mastering the Roof by GAF

Essentially, both of these types of flashing do the same thing they help guide water away from seams and joints in your roof, preventing water from soaking through your shingles, or in-between vulnerable joints.

L-shaped flashing is, as the name may suggest, shaped like an L, built with a simple 90-degree joint that flares out at the bottom. The L shape hugs the side of your roof tightly, while the flared base pushes water away from your siding, keeping your home more dry.

T-shaped flashing is slightly different. Shaped like an elongated T, this flashing attaches to the roof and projects outward, with a downward projection that sits an inch or two outside away for the side of your home.

The increased distance between your home and the flashing itself makes T-shaped flashing, a better overall choice when youre going to install flashing on an existing roof. Water will run more smoothly across the flashing, and be pushed farther away from your home, helping you avoid excess moisture that can damage your siding.

How To Install Counter

Chimney flashing should be installed at the same time the mason is laying the brick and mortar, or the roofer will have to cut a ridge out for the counter-flashing. Then, the roofer will have to seal this indent up, after placing the flashing.

  • Step One: Ensure the chimneys base flashing is in proper order, secured to the roof as the manufacturer or mason recommends, beneath the shingles. If you were not provided with base flashing, you can install step flashing up the side of the chimney.
  • Step Two: Cut an indent into the chimney with a diamond bit saw/diamond grinder disc. This is where you will hang the counter-flashing.
  • Step Three: Insert the counter-flashing to the indent. Be sure that it hangs so that it overlaps with the base flashing by at least 2 inches.
  • Step Four: Use roofing cement to secure the counter-flashing to the base flashing and the chimney.
  • Step Five: Seal the indent with roofing caulking, so the counter-flashing hangs securely.

Counter flashing on a chimney

Tools Needed To Flash Your Metal Roof To A Wall

As mentioned above: To flash a metal roof to a wall, you will need: Metal roofing panels, Flashing tape or self-adhesive flashing strips, Sheet metal screws that are galvanized for exterior use.

Metal Roofing Panels The type of panels you choose will depend on the purpose for your installation.

If you are flashing a metal roof onto an existing wall, any exposed fasteners should be covered with sheet metal to prevent leaks and provide additional support against wind uplift or other forces that might cause movement in the panel.

Flashing Tape Flash tape is a self-adhesive product that can be used for different types of flashing.

It should come with instructions for installation and may require the use of sealant to ensure a proper bond between materials.

Sheet Metal Screws To complete your job, you will need galvanized screws long enough to go through each panel and penetrate into the houses siding by at least one inch.

Whether you are building a new structure or repairing an existing wall, flashing the metal roof to the surface is easy if you follow these three simple steps: apply sealant on exposed edges and corners of the roofing panels as well as over any penetrations such as valleys and hips install sheet metal screws long enough to go through the panel and penetrate into the houses siding by at least one inch flash any areas where a valley may be exposed due to a dormer or chimney.

Read Also: Should I Replace The Screws On My Metal Roof

How To Repair Roof Flashing

Before getting into the specifics of various flashing repairs, it should be mentioned that it is wisest for the homeowner to have all previous flashing taken off before having new roof flashing installed. If only parts of the old or damaged flashing are replaced, it will likely fail before the new flashing lifespan is over.

However, it is possible for professional roofers to salvage flashing that is still intact when removing the old or damaged pieces. The roofer will have to first inspect the flashing to assure it will continue doing its job efficiently then, if finding that some flashing pieces are still useful, the roofer will attempt to remove the damaged flashing without damaging the rest.

Not all types of flashing are easily removable without causing damage to each of the flashing pieces. In most cases, it makes more sense to remove the entire row or line of flashing and install fresh flashing.

The following is designed to help you understand what goes into flashing repair. For the homeowner considering installing or repairing the flashing him/herself, see the subsection below.

Flashing can be repaired in a few steps:

  • The shingles surrounding the flashing should be gently lifted so as to not be damaged.
  • The flashing needs to be removed, whether the homeowner decides on only pulling off damaged flashing or all flashing. This can be done by carefully chiseling away the sealant or taking out the nails.
  • Only Nailing On One Side To Allow For Movement

    What are Roof Flashing Materials and What are They Used ...

    Its important to remember that a building always is moving. If you nail step flashing to the wall and to the roof, youre asking for trouble. Most of the time, I like to avoid putting any extra holes in the roof surface, so I nail step flashing to the sidewall only, where both the next piece of flashing and the siding will cover the nail head. The bottom corner, where you start the course of flashing, is made from two pieces of bent step flashing lapped over each other and caulked in place.

    Also Check: Skylights In Metal Roofing

    How To Install Step Flashing

    this infographic.

    You can purchase pre-cut step flashing pieces or you can cut pieces yourself from a longer piece of metal. Cut the pieces of flashing into strips 10 inches wide. Then cut each piece to 3 inches longer than the shingles exposure. You want it to be able to overlap the piece that is installed below it. The 10-inch length will be bent in the middle to provide 5 inches of flashing material on the wall and 5 inches on the roof surface. Bend each piece of flashing by hand to a right angle.

    Each piece of step flashing is installed in a type of weave pattern. Each unit of step flashing overlaps the shingle below and is positioned under the shingle above. The first piece of flashing is installed so that it is resting on a shingle. Nail the flashing on the wall side, placing a single nail high enough to be covered by the next piece of flashing, the building wrap, and the siding. For added protection, you can apply sealant to the overlapping areas of the flashing.

    Lay a whole shingle course above this flashing piece. Then you will lay the next piece of step flashing where the next row of shingles will start, overlapping at least 3 inches. Keep alternating between shingles and flashing until the roof deck area is covered.

    The top of the step flashing should be covered with house wrap and then siding. Take care not to nail through the tops of the flashing when you are installing the siding.

    What Flashing Depth Into A Wall

    If youre cutting a new chase into the mortar between two brickwork courses you will often see the measurement of 25mm recommended as the minimum depth for lead flashings to be set into a chase.

    Keep in mind the depth of 25 mm is a quarter of the width of your remaining mortar. This is absolutely fine until the brickwork becomes unstable, this can happen for several reasons and must be considered before setting this as your chosen depth.

    • Old brickwork On old properties and chimneys the mortar can become loose or sandy, the deeper you cut the higher the likelihood of loose bricks.
    • Windows and lintels The strength and bond of these bricks may be compromised and can become loose easily.
    • Shoddy bricklaying Even on new builds Ive known the rear unseen or unaccessible face of the brickwork to be gappy, 25mm removed from the front face may not help matters.

    For these reasons and more, I prefer a depth of 15 20mm, and if you ever renew old lead flashings, you will probably find this to be common practice amongst other roofers too.

    Chasing out The process of removing the old mortar can be done with a small angle grinder with a diamond raking disc, preferably using dust extraction, or with a dedicated mortar raking tool. This is often called raking out or cutting a chase.

    What lead thickness for roof flashings

    Lead code table This chart shows common milled lead codes including weight and thicknesses.

    Can I use code 3 lead for flashings ?

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    Prevent Water Damage With Step Flashing

    The outside of your home should have cladding to prevent water damage. This is a layer attached to the outside of the walls, such as siding, and the roof material of your home, usually roofing shingles. Step flashing is a set of small L-shaped pieces of metal that are woven into the roofing shingles during shingle installation. The flashing connects the roof cladding with the wall cladding in a way that keeps water out.

    The use of step flashing is critical to installing a watertight roof.

    Because of their importance, flashing materials should meet or exceed the life expectancy of the roof. Flashings often connect different moving components, so they should be able to accept thermal and load-induced movement, especially if they are located above an expansion joint, explains Erin Falvey, a project engineer at Facility Engineering Associates.

    Step flashing is installed so that there is a row of short pieces of flashing for every row of shingles. Each piece of step flashing will be overlapped by the shingle below. The flashing along the wall extends up behind the exterior covering.

    Step flashing is made from stainless or galvanized steel, copper, lead, or aluminum. Corrugated aluminum metal flashing is the most affordable type of flashing. Step flashing is usually an installation and code requirement for asphalt, wood, and slate shingles.

    How To Install Step Flashing On Your Roof

    How to Install Roof Flashing on a Shingle Roof – IKO
    • Working Time: 1 hr, 30 mins
    • Total Time: 2 hrs
    • Yield: 6 feet of step flashing
    • Skill Level: Intermediate
    • Estimated Cost: $50 to $75

    An effective system of step flashing on a roof is crucial to maintaining not just your roof but your entire home. Mold, rot, insects, and structural failure are the main byproducts of moisture intrusion inside walls, attics, roofs, and floors. Learn how to install step flashing to keep your house dry and in good condition.

    Read Also: Cost Of New Roof California

    Where Should I Install New Flashing

    Flashing is generally installed at any joints or edges in the roof where water could otherwise work its way in.

    In order to properly install new flashing, youll have to remove the shingles surrounding your old flashing, and then re-lay them after installation. Typically, flashing is installed using roofing nails and roofing cement. After installation, youll then re-lay the shingles you removed, to provide a comprehensive, water-tight solution.

    Flashing can be purchased in pre-formed styles to help you install it more easily, and these include:

    • Step Flashing built to protect joints between roofs, chimneys, and other objects like skylights, this flashing steps up above the shingles and attaches to the object, providing comprehensive water protection.
    • Vent Pipe Flashing as the name implies, this flashing is usually cylindrical, with a large, flanged based that allows you to lap it into your shingles during a roofing project.
    • Valley Flashing This flashing is usually formed in a V or W shape, and is used where two different roof planes meet, forming a valley.
    • Drip Flashing Also called drip edge, this type of flashing is installed on the edge of roofs, and helps guide water away from your roof and into your gutters.

    Lets take a deeper look at drip flashing now.

    How To Install Roof Flashing In 2021

    Roofers use roof flashing to ensure no water leaks into areas of roofing features like vents, chimneys, dormers, skylights, etc. Its critical during roof installation to avoid any damage in the future and helps uphold the integrity of a new roof.

    However, flashing may need to be replaced throughout the lifespan of a roof, so we will walk through the steps of installing or replacing roof flashing. Pay close attention to keep your roof safe from leaks and water damage.

    Read Also: Cost To Reseal Rv Roof

    Installing Flashing: Eave Trim

    Some metal roof trim pieces are used to keep water away from the roof fascia. These pieces are known as eave trim. When rain lands on your roofing, this type of trim directs it to the ground so that it never comes into contact with the fascia.

    Before installing flashing like eave trim, its important to set an underlayment before placing the metal pieces. This underlayment helps to prevent moisture penetration.

    Installing this type of trim is a bit easier than installing rake trim. While eave trim does need to be cut and folded to fit the fascia and gable, it requires minimal angling to make a proper fit.

    The last step is to use screws again, between 12 and 24 inches apart to fasten the eave trim in place.

    How To Install Roof Flashing Under Siding

    âHow to Perform Roof Inspectionsâ? Course

    When placing flashing against the siding, the technique that you will be most likely to use will be step flashing. To do that, you will need the following equipment:

    • Flashing pieces
    • Siding brake

    Step 1: Cut.

    The first step is to cut a sheet of flashing. There are sheets of flashing available in the market today, which many experts tend to rely on. However, roof flashing is not a one size fits all, and the size you need might not be available for purchase.

    In that case, its best to cut your flashing. For roof flashing against the siding, it should beat least4 inches or 102mm wide. The size, however, may vary depending on the siding.

    Step 2: Install and insert.

    Next, install a piece of lap siding. Nail it using the recommended method. Once installed, insert a piece of pan flashing vertically under the one end of the siding.

    When inserting, make sure that the flashing below does not go beyond the lap siding.

    Step 3: Secure.

    Finally, secure both the flashing and siding by fastening them together into the structure. Once completed, simply repeat the process until the whole house is covered. Do not forget to leave at least 3/16 inches between the pieces of siding.

    Also Check: How Much Roof Overhang On Shed

    How To Install Roof Flashing

    Disclaimer:Roof flashing should always be installed by professional roofers, who understand best practices, safety requirements and the building codes and laws in their area. These instructions are only to help homeowners understand what to expect from their roofing professional.

    Step flashing is the most time-consuming of all flashing jobs on the roof because you must complete it step-by-step as you shingle up the roof. There are a few general best practices you need to know. First, step flashing must be installed before the siding, so that the siding can cover the top of the flashing. If this is a repair job, the siding must also be removed and replaced with the flashing. Second, step flashing needs to extend 8 to 14 inches above the shingles, according to the National Roofing Contractors Association .

    Also, before you start installing your flashing, you need to look to see if the wall in question has a corner on the roof face, as in the image below.

    If it does, follow our first installation procedure. If it doesnt have a corner, and simply looks like the image below, follow the second installation procedure.


    Step roof flashing no wall corner

    The Other Roofing Materials Every Homeowner Needs To Know

    You just learned what roof flashing is and 3 things you need to know about it. Flashing is a critical part of your roof that should always be checked out during annual roof maintenance.

    But roof flashing is just one roofing material that you need to know about. That’s why we have another article breaking down the 9 crucial roofing materials that make up your roof.

    Since 1990, the team at Bill Ragan Roofing has been repair and replacing roof systems in Nashville and surrounding areas. Our workmanship ensures you get a new roof that lasts for decades.

    Read Also: Replacing Roof Trusses

    What Is A Roof Flashing And Why Is It Important

    While roofs are purposely constructed to allow rainwater run-off, they can often have several vertical features or protrusions, such as chimneys, parapet walls, half walls, dormers, skylights, vent pipes, and the like, where water can pool up and/or drip into the crevices between. The areas can eventually become damaged and allow water seepage and leaks into the house. To prevent this, professional roofers apply roof flashing to divert rainwater down the sides of the vertical surfaces, keeping the water from stagnating.

    Roof flashing is typically a thin metal material fabricated from rust-resistant metal, such as G-90 galvanized steel, a frequently used flashing material, copper, or aluminum. Depending on the company, flashing may even be available in lead or zinc alloy.

    Steel, copper, and aluminum are particularly used because of how malleable these metals are, rendering them easier to shape. However, the homeowner should note the different characteristics of each metal:

    Flashing closes the joints between the roof and the roof features in order to protect the house from erosion and leaking. A lack of flashing or poor flashing installation can also lead to wood rot, potential shingle damage, or deck collapse, among other issues.

    Flashing comes in various shapes and is used for different areas on the roof . For this reason, different flashing types will be installed in dissimilar ways, and the cost of flashing will vary.


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