The Ultimate Guide to Flashing on a Metal Roof

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Ahoy there, brave DIY homeowner! Are you ready to tackle the nitty-gritty of flashing on a metal roof? Well, you’ve come to the right place! Our Ultimate Hitchhiker’s Guide to Flashing on a Metal Roof will walk you through the process step by step. We’ll spill the beans on the best materials, techniques, and tools for the job. So, buckle up and let’s dive into the wild world of flashing!

1. The ABCs of Metal Roof Flashing: Why It’s the Bee’s Knees

a. The Purpose of Flashing: Seal the Deal

Flashing is the unsung hero of your metal roof, acting as a watertight barrier that prevents leaks. Without flashing, water could easily seep into your home, causing all sorts of damage to your roof, walls, and even your belongings. That’s why it’s so important to have a proper flashing system in place. The main goal of flashing is to direct water away from vulnerable areas, such as joints and seams, and off your roof. By doing so, flashing ensures that your roof stays watertight, and your home stays safe and dry.

b. Flashing Types: Many Shapes, Sizes, and Styles

There are various types of flashing designed to protect specific areas of your roof. Here are some common ones:
  • Valley flashing: Used in the valleys where two roof slopes meet, creating a water channel.
  • Drip edge flashing: Installed along the eaves and rake edges to prevent water from seeping under the roofing material.
  • Step flashing: Used where a roof meets a vertical surface, like a chimney or sidewall, to direct water away from the joint.
  • Vent pipe flashing: Designed to seal around vent pipes, preventing water from entering the roof around the pipe.
  • Chimney flashing: Installed around the base of a chimney to seal the joint between the chimney and the roof.
Each type of flashing has a unique purpose and design, but they all work together to create a watertight barrier on your metal roof.  

2. Choose Your Weapon: Picking the Perfect Flashing Material

a. Aluminum: The Lightweight Champion

Aluminum is a popular choice for flashing on a metal roof due to its lightweight nature and easy workability. It’s corrosion-resistant, making it a suitable option for homes in coastal areas or those exposed to harsh weather conditions. However, aluminum is not as durable as some other materials and may need to be replaced more frequently.

b. Copper: The Golden Child

Copper flashing is a premium choice that adds an elegant touch to your roof. This material is incredibly durable and can last for decades without needing to be replaced. It’s also naturally corrosion-resistant and can develop a beautiful patina over time. However, copper flashing is more expensive than other materials, so it may not be suitable for every budget.

c. Steel: The Sturdy Workhorse

Steel flashing is a durable and cost-effective option for homeowners looking for a reliable material. Galvanized steel has a protective zinc coating that provides excellent corrosion resistance, while stainless steel offers even greater durability and strength. Both types of steel flashing can be painted to match your metal roof or home’s exterior.

d. Zinc: The Eco-Friendly Superstar

Zinc flashing is an eco-friendly and highly durable option for your metal roof. It’s naturally corrosion-resistant and requires little maintenance over time. Zinc also has a unique self-healing property, which means that minor scratches or damage can be repaired naturally as the material weathers. While zinc may be more expensive upfront, its longevity and low maintenance make it a worthwhile investment for many homeowners.   fabric awning cover over solar panels to protect from storm damage

3. Measure Twice, Cut Once: Prepping for Flashing Installation

a. The Right Tools for the Job: Assemble Your Flashing Arsenal

Before you begin installing flashing on your metal roof, you’ll need to gather the right tools and materials. Here’s a quick checklist of essentials:
  • Tape measure
  • Straightedge
  • Utility knife
  • Tin snips
  • Caulking gun
  • Roofing sealant
  • Roofing nails or screws
  • Hammer or screwdriver
  • Gloves and safety goggles
Having the right tools on hand will make your flashing installation process smoother and more efficient.

b. Measuring and Cutting: Precision is Key

Proper measuring and cutting are crucial when it comes to flashing installation. Start by measuring the area where the flashing will be installed and carefully mark the dimensions on the flashing material. Use a straightedge to ensure that your lines are straight and accurate. Then, using your tin snips or a utility knife, carefully cut the flashing along the marked lines. Remember, it’s always better to measure twice and cut once to avoid making mistakes that could lead to wasted materials or an improper fit.

4. Flash Dance: Installing Flashing on Your Metal Roof

a. Step by Step Guide to Flashing on a Metal Roof: Follow the Yellow Brick Road

  1. Clean the installation area: Remove any debris, dust, or dirt from the area where the flashing will be installed. This will help ensure proper adhesion of the sealant and a watertight seal.
  2. Apply roofing underlayment: If not already in place, install roofing underlayment as a barrier between the metal roof and the flashing.
  3. Install base and step flashing: Starting at the bottom, install the base and step flashing pieces according to the manufacturer’s instructions. Be sure to overlap each piece by at least 2 inches and secure them with roofing nails or screws.
  4. Add counterflashing: Install counterflashing over the top edge of the base and step flashing to create a watertight seal. This will help divert water away from the roof and prevent leaks.
  5. Seal the seams and edges: Apply a bead of roofing sealant along the edges of the flashing and at any seams or joints to create a watertight seal.
  6. Inspect and maintain regularly: Check your flashing periodically for signs of damage or wear and make any necessary repairs promptly.

b. Pro Tips: Secrets from the Flashing Masters

  • When overlapping flashing pieces, always place the upper piece over the lower piece. This helps direct water away from the roof and prevents leaks.
  • Use a high-quality roofing sealant that’s compatible with your metal roof and flashing materials. This will help ensure a long-lasting, watertight seal.
  • Be mindful of expansion and contraction due to temperature changes. Allow for some movement in your flashing installation to prevent buckling or damage.

5. Troubleshooting Tips: Common Flashing Faux Pas

a. Leaks: Patch ‘Em Up

If you notice a leak around your flashing, don’t panic! First, identify the source of the leak, and then clean and dry the area thoroughly. Apply a generous amount of roofing sealant to patch the leak and create a watertight seal. If the leak is severe or the flashing is damaged, you may need to replace the affected section.

b. Loose Flashing: Secure Your Work

Loose or poorly secured flashing can lead to leaks and damage over time. If you notice any loose flashing pieces, reattach them using roofing nails or screws, making sure they’re properly aligned and overlapped. Finish by sealing the edges with roofing sealant to create a watertight barrier.

c. Maintenance and Inspection: An Ounce of Prevention

Regular maintenance and inspection are key to keeping your metal roof flashing in top-notch condition. Keep an eye out for any signs of wear, damage, or corrosion, and address any issues promptly. Clean your flashing periodically to remove dirt, debris, and any buildup that could cause damage or reduce its effectiveness.


Q: What’s the best material for flashing on a metal roof?
A: The best material for your flashing will depend on factors such as your budget, location, and desired aesthetics. Aluminum, copper, steel, and zinc are all popular choices, each with its own benefits and drawbacks.

Q: How do I install flashing on a metal roof valley?
A: To install valley flashing, first lay down a layer of roofing underlayment in the valley. Then, center the valley flashing over the underlayment, making sure it extends past the eave edge. Secure the flashing with roofing nails or screws, and seal the edges with roofing sealant.

Q: How often should I inspect and maintain my metal roof flashing?
A: It’s a good idea to inspect your metal roof flashing at least twice a year, as well as after any major storms or extreme weather events. Regular maintenance, such as cleaning and sealing any gaps or cracks, will help extend the life of your flashing and prevent leaks.

Q: Can I install flashing on a metal roof myself, or should I hire a professional?
A: Installing flashing on a metal roof can be a DIY project if you’re comfortable working on a roof and have the necessary tools and knowledge. However, if you’re unsure or inexperienced, it’s best to hire a professional to ensure a proper installation.


And there you have it, folks! With this Ultimate Guide to Flashing on a Metal Roof, you’re now well-equipped to embark on your flashing installation journey. Remember, practice makes perfect, so take your time and measure twice. Your metal roof will be watertight and looking spiffy in no time.   If you’re intrested in sunrooms we have a full guide here.

Last Updated:June 03, 2023