Metal flashing plays a critical role in protecting vulnerable areas in a roofing system. Although the main roofing material across a roofing system handles the majority of water protection for a roof, flashing takes care of the areas where penetrations occur or where two surfaces meet. This article will explore what metal flashing is and how it benefits your client’s roofing system.

Your Guide to Metal Roof Flashing

We developed this guide as a reliable resource for your team to reference on-site or consult when tackling complex builds. It is a great way to brush up on the essentials, highlighting the importance of proper metal roof flashing while covering material compatibility, how it handles the elements, and what a proper installation looks like. Feel free to use this guide to verify specific details or skip directly to the sections most relevant to your current project.

What is Metal Flashing?

Metal flashing is a thin material, typically galvanized steel or aluminum, installed to direct water away from critical areas of a roof. You will find it anywhere the roof plane meets a vertical surface, such as a wall or dormer, or around any penetration. This includes roof features such as:

  • Chimneys
  • Wall junctions
  • Roof valleys
  • Dormers
  • Skylights
  • Pipe penetrations

When it comes to the materials used in roof flashing, durability and compatibility are key. The most common choices include:

  • Galvanized Steel: Preferred for its strength, durability, and affordability, steel is an intelligent choice for most roofing systems. It is robust enough to support the weight of water-filled gutters and withstand extreme weather conditions. Most building codes require at least 26-gauge galvanized steel.
  • Aluminum: Known for its low maintenance and corrosion resistance, aluminum flashing is lightweight and easy for professionals to form on-site. While it can last 30 years or longer, it must be coated if it will be in contact with concrete or masonry, as a chemical reaction can cause it to degrade.
  • Copper: For a premium look and superior longevity, copper is an excellent choice. It is highly durable, solder well, and develops a classic green patina over time that many homeowners favor. While more expensive, it is often used for chimneys and custom architectural details.

This versatility allows homeowners and builders to choose a material that complements the overall design of the building. Whether you’re considering standard metal flashing panels for a cost-effective solution or opting for custom metal flashing panels to achieve a unique aesthetic, Metal Formers is ready to help you evaluate your roofing project to find the option that best fits.

What Kind of Roof Flashing Should be Used on a Metal Roof?

When you are building a metal roof, you want to use metal flashing made from the exact same material as your roof panels, whether that is steel, aluminum, or copper, to keep galvanic corrosion from ruining your hard work. Depending on the layout of your build, we can help you determine exactly when to use custom-bent trim, standard roll flashing, or specialized pipe boots to ensure every flashing roof connection stays leak-proof and holds up for the long haul.

There are a few reasons why matching your roof flashing material to your roof matters: 

  • It stops harmful chemical reactions: When two different metals come into contact and get wet from rain or condensation, they can trigger galvanic corrosion. This causes the metals to rust and break down way faster than they should.
  • Everything expands at the same rate: Metals expand and contract with heat and cold. Using the same material means your flashing and panels move together, preventing gaps and leaks.
  • The lifespans match up: You don’t want your flashing failing years before your roof panels do. Matching materials ensures they both go the distance together.
  • It looks more cohesive: Using the exact same metal gives the whole roof a clean, seamless, and unified look.

The Main Types of Roof Flashing

Different areas of a roof require uniquely shaped flashing to ensure water is channeled correctly. While we can custom-fabricate any piece you need, it’s helpful to understand the most common types:

  • Step Flashing: Used where a roof meets a side wall, like the side of a chimney or dormer. Rectangular pieces of flashing are installed in layers, interwoven with each shingle course in a “step” pattern to block water from running down the wall and behind the siding.
  • Counter Flashing (or Cap Flashing): This is the second piece of a two-part system often used on chimneys. The counter flashing is embedded into the chimney’s mortar joint and overlaps the top of the base or step flashing, creating a protective cover that allows the roof to expand and contract without breaking the seal.
  • Valley Flashing: In “open” roof valleys where two roof planes meet, a solid piece of W-shaped metal is installed down the center of the valley. This flashing prevents water from getting underneath the roofing materials as it rushes down this high-flow area.
  • Vent Pipe Flashing: These are cylindrical sleeves that fit over pipe penetrations. They have a flange at the bottom that is integrated with the roofing material to create a watertight seal around the pipe.
  • Kickout Flashing: A small but critical piece placed where a roof edge terminates against a wall. Its purpose is to “kick” water away from the wall and direct it into the gutter, preventing water from running down the siding and causing rot.

What is Drip Edge in Metal Roofing?

A drip edge is a specific type of metal flashing that is installed around the edges of a roof to redirect water away from the fascia and underlying components. With metal roofs, the drip edge protects the decking and fascia while creating a finished look that will leave your client satisfied. Although other types of roof flashing also protect roofs from water damage, the drip edge is uniquely designed to prevent water from being able to flow back up underneath the roof deck or fascia.

How Does a Drip Edge Protect Your Home?

  • Controls the flow of water: A drip edge prevents water from clinging to the underside of roofing materials and flowing back toward the fascia or roof deck, instead of flowing off the roof into the gutters. 
  • Prevents wood from rotting: Without a drip edge, water can become trapped in tight spaces between metal roofing components and panels. The drip edge also prevents water from becoming trapped in tight spaces between metal roofing components and panels. Over time, this can lead to wood rot, molding, or compromised gutter attachments. 
  • Manages pests and insects: A roof deck or fascia often leaves small gaps where animals and insects can crawl into your attic. A drip edge helps seal off these gaps completely and keep your home free of unwanted guests.
  • Provides structural reinforcement: In areas like Tennessee, a drip edge provides structural reinforcement to the edges of roofs during strong thunderstorms, seasonal rain, and tornadoes, making it essential for maintaining more than just building codes.

With Metal Formers, Inc., you can secure custom-fabricated metal drip edges that will match the exact dimensions and style of your client’s roof. To see the types of drip edges we can custom fabricate for your roofing project, check out our trim and flashing page for a full list.

Why Is Proper Metal Flashing So Important?

Proper metal flashing helps protect the most vulnerable areas of a roofing system by directing water away from joints, seams, and penetrations. Without properly installed flashing, moisture can enter the roof system and lead to leaks, structural damage, and costly repairs over time. 

The key benefits of proper flashing include:

  • Preventing Water Intrusion: Properly installed flashing creates a watertight barrier around roof penetrations, transitions, and intersections to help keep moisture out of the roofing system.
  • Extending Roof Life: By protecting the areas most susceptible to leaks, quality flashing helps preserve the roof deck and surrounding components, contributing to the long-term performance of the entire roofing system.
  • Supporting Energy Efficiency and Code Compliance: Flashing helps seal vulnerable areas against air and water infiltration, improving the building envelope while also helping meet applicable building code requirements, including drip edge requirements for new construction and reroofing projects in Tennessee.

Best Practices for Proper Metal Roof Flashing Installation

To ensure your installations maintain the highest standards of durability, there are a few key practices to review. Implementing these straightforward methods will help eliminate common installation errors and protect the integrity of the roof, making sure there is a professional finish on every project.

  • Be mindful of screws: Avoid driving screws into high-water areas, like the center of flashings. Stick to the edges instead, and always use screws with rubber gaskets to seal things up tight.
  • Don’t make pipe boots too tight: When you trim an EPDM boot, don’t make it a struggle to get on. If you stretch the rubber too tight over the pipe, it is bound to split and crack.
  • Don’t overuse sealant: Sealant is a backup, your real defense against leaks is a solid metal-to-metal overlap. When you do use sealant, just make sure it is specifically rated for metal jobs.
  • Clean up leftover debris: Always sweep away metal shavings and burrs right after cutting your panels or flashing. If you leave that debris sitting on the roof, it will ruin the paint finish and cause rust spots.

Disclaimer: Roof flashing installation requires specialized expertise. For your personal safety and to protect your roof’s structural integrity, this work should only be performed by a licensed professional roofer.

The Value of a Metal Company That Custom-Fabricates Flashing

Although standard flashing panels can get the job done, custom-fabricated flashing from a metal fabrication company like Metal Formers can provide numerous benefits that will enhance your next roofing project. When you use custom flashing from Metal Formers, you can expect:

  • Perfect Fit for Unique Roof Designs: Roofs with unusual transitions, complex designs, and irregular penetrations can easily be fitted precisely with made-to-order flashing designed for the specific project.
  • Improved Performance: The water-tight seal and reliable drainage routes custom-fitted flashing to create longer-lasting results than standard flashing.
  • Superior Aesthetics: With custom-fabricated flashing, you can select a custom color and material to seamlessly blend into the roof and architecture.
  • Better Material Selection: Custom-fabricated flashing can be produced in the exact material and gauge your project needs for any environment.
  • Faster Turnaround and On-Site Adjustments: Working with a local metal company such as Metal Formers reduces lead times and makes it easier to make last-minute changes on-site.
  • Consistent Quality Control: Mass-produced standard flashing goes through less quality assurance than custom-fabricated flashing.

Overall, when you work with a custom-fabrication metal company like Metal Formers, you get a partnership that creates more precision, flexibility, and reliability to create roofing systems that keep your client’s home protected and looking great.

Why Full Flashing Replacement is the Professional Standard

As a professional, you know that a new metal roof’s performance is only as good as its most vulnerable points. While existing flashing might look serviceable, tying your workmanship to another contractor’s install from 20 years ago is a significant risk.

Recommending a full flashing replacement on a reroof job isn’t an upsell; it’s a best practice for several reasons:

  1. System Integrity: It ensures all roofing components from the panels to the flashing are new and will age uniformly. This simplifies service life expectations for your client.
  2. Mitigating Liability: Reusing old flashing makes you responsible for the quality of the previous installation. If that old flashing fails, the callback will be on your company, regardless of how well you installed the new panels.
  3. Preventing Damage: Attempting to work new metal panels or underlayment around old, embedded flashing can compromise the new materials and damage adjacent surfaces like walls or chimneys.
  4. Guaranteed Performance: Installing new, custom-fabricated flashing is the only way to guarantee a watertight seal that matches the longevity of the new metal system. It protects your reputation and ensures a leak-free result for the property owner.

Roof Flashing Inspection and Failure Analysis

During maintenance inspections or service calls, accurately diagnosing flashing failure is key to preventing costly water intrusion. While quality metal flashing is designed for long-term performance, weather exposure, aging, and installation errors can eventually cause it to deteriorate.

Key indicators to look for during your assessment:

  • Rust or Corrosion: This is common on older, non-galvanized, or G60 steel flashing, especially where the coating was scratched during installation or at fastener points. This weakens the metal and will lead to perforation.
  • Loose or Lifted Sections: Often caused by improper fastening, high winds, or a failure to account for thermal expansion. Look for broken sealant bonds and gaps, especially on long, continuous runs or at improperly secured counter-flashing.
  • Sealant Failure: Mastics and sealants used at the edges of flashing will inevitably dry out, crack, and lose adhesion over time. This creates a direct path for water infiltration and is a common failure point.

While localized sealant failure or a single loose fastener might be serviceable, widespread corrosion, deformed metal, or clear signs of improper original installation (e.g., reverse laps, missing step flashing) demand a full replacement. Advising a full replacement in these cases is the only way to professionally guarantee the system’s long-term performance and protect the structure.

The Role of Fascia Metal in Roofing Systems

Metal Formers employees installing a metal roof.

Fascia metal is an important finishing component that protects the roof edge, supports gutter systems, and enhances the overall appearance of a building. Installed along the roofline, it helps shield exposed fascia boards from moisture, pests, and weather while providing a clean, finished look. When used alongside properly installed flashing, fascia metal contributes to the long-term durability and performance of the roofing system.

Metal Formers fabricates custom fascia metal in a variety of colors, gauges, and profiles to complement residential and commercial roofing projects. Whether your project requires standard fascia trim or a custom solution, selecting the right material and profile helps ensure lasting performance and a professional finish.

Metal Roofing with Metal Formers, Inc.

Understanding the different types of metal flashing, fascia, metal trim, and roofing components can help you make informed decisions for your roofing projects. By investing in quality fascia metal and following best practices for its care, you can make sure your roof lasts longer while still looking fantastic.

At Metal Formers in Nashville, TN, we offer a variety of metal panels, trims, and flashings that can be made with any gauge to make your metal roof look outstanding. We can help you determine the best fascia pieces for your next roofing project and ensure your clients get a customized, high-quality metal roof. You can find more information about the metal fabrication options we provide online and view some of our residential roofing work.

If you have additional questions about Metal Formers and our products, feel free to connect with us online. For online orders, visit our order form page to download the order form for the products you need. Once completed, you will want to send your form to us via email at office@metalformersinc.com.

When it comes to protecting your roof and making your roof last, the team at Metal Formers is eager to assist you with any home improvement needs! We look forward to hearing from you.

Frequently Asked Questions About Proper Roof Flashing

How Important Is Flashing on a Roof?

Roof flashing is one of the most important components of a complete roofing system. It is installed in areas most vulnerable to leaks, such as valleys, chimneys, and wall intersections. Without proper flashing, water intrusion and damage are not just possible, but guaranteed.

What Kind of Flashing Should be Used for Metal Roofing?

Always match your metal flashing to your roof panels, like steel with steel, to prevent corrosion. When two different metals touch and get wet from rain or condensation, they trigger a chemical reaction that causes them to rust and degrade very quickly. Using the same material also means everything expands and contracts at the same rate, lasts just as long, and looks great together.

What Happens If You Don’t Have Roof Flashing?

If a roof does not have flashing, or if the flashing is installed incorrectly, water will penetrate the roof deck. This leads to wood rot, damaged insulation, interior water stains, and eventually, dangerous mold growth that can affect your health.

Can Missing Flashing Cause Mold?

Yes. Missing or failed flashing is a primary cause of slow, persistent leaks that create damp, dark environments inside your attic or walls. These are ideal conditions for mold and mildew to grow, which can spread undetected and compromise your home’s air quality.

How Expensive Is Roof Flashing?

The cost of roof flashing depends on the material chosen, the complexity of the roof design, and whether it’s part of a repair or a full roof replacement. Galvanized steel is the most budget-friendly option, while copper is significantly more expensive. Custom-fabricated flashing offers the best long-term value by preventing costly water damage repairs.

What are the Maintenance Requirements for Roof Flashing?

Roof flashing should be inspected at least twice a year and after severe storms. Regularly clearing debris and promptly repairing damaged, corroded, or loose flashing helps prevent water intrusion and extends the life of the roofing system. This regular upkeep helps prevent expensive water damage to your home. 

What Is the Lifespan of Roof Flashing?

The lifespan depends on the material and climate. High-quality metal flashing made of steel, aluminum, or copper can easily last for decades and may even outlast a single set of asphalt shingles. Proper installation is the most critical factor in ensuring its longevity.

Where Is Flashing Required by Code?

Most building codes, including the International Residential Code (IRC), require flashing to be installed at roof-wall intersections, around chimneys, and at all roof penetrations. Drip edge flashing at the eaves is also typically required for new construction and re-roofing projects.

Can I Install My Own Roof Flashing?

Although it is possible to install roof flashing yourself, we strongly recommend hiring a licensed professional to ensure it is code and warranty-compliant. If flashing is installed incorrectly, it can lead to a lot of problems, such as severe water damage to your roof.