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Metal Roof Flashing Installation: Steps, Tips, Dos & Don’ts

Posted on : September 1, 2023

Metal Roof Flashing Installation: Steps, Tips, Dos & Don’ts

Are you looking for some expert tips on installing flashing on a metal roof? As a seasoned roofing professional with years of hands-on experience, I've put together this guide to help you through the installation process. In this blog post, I'll walk you through the steps for a successful installation, offer some valuable tips, and share the dos and don'ts that can help you ensure a flawless finish.

What Is Flashing On a Metal Roof?

Typically composed of durable materials such as galvanized steel, aluminum, or copper, flashing is a thin, flat metal strip that is custom-fit to the specific angles and contours of a roof. It works to seal all types of roofs, including metal roofs. You can find flashing on a metal roof in areas where the roof intersects with other elements like the fascia, skylights, walls, chimneys, and vents.

But without proper installation, metal roof flashing can not provide protection against water damage.

Flashing a Metal Roof: A Step-by-Step Guide

Follow this installation guide to avoid costly mistakes and repairs later on.

Metal Roof Flashing

Step 1: Preparation 

As you’re getting started, remember proper preparation is essential. Gather your tools, such as metal snips and sturdy gloves, to ensure safety and efficiency. Consider carrying extra tools in case something is not up to the mark. 

Assessing the Terrain

Start by examining the roof's layout. Identify critical areas where flashing is needed, including valleys, chimneys, skylights, and dormers. This assessment will be your guide for completing the project, including how much material is required. After that, make sure the roof is clean and free of debris. The installation process will go much smoother if there is a clear surface to work on.

Step 2: Selecting the Right Materials

Choosing suitable materials is crucial for a successful installation. I recommend using sturdy metals, like aluminum and copper, that provide both durability and aesthetic value, while galvanized steel is an affordable yet long-lasting choice.

Cutting and Shaping

Once you've selected your metal, cut and shape it accurately to fit the designated areas. Precision is essential here, as ill-fitting flashing will not protect against water damage. 

Step 3: The Installation Process 

Here are the steps for installing metal roof flashing. 

Begin by securing the base flashing, creating a stable foundation. Add step flashing around walls and valley flashing along intersections. Each layer contributes to a seamless flow of water, creating a waterproof roofing system. 

Ensuring a Watertight Bond

It's crucial to ensure that every piece of flashing seamlessly integrates with the roofing material, forming a watertight seal. 

Step 4: Final Touches

After successfully installing the flashing, it's time to add the finishing touches. Seal the edges with a high-quality metal roof sealant to prevent water infiltration. This will ensure water does not seep under the edges of the flashing, further protecting your home.


Apply a weatherproof coating to the metal, shielding it from the elements. This coating serves as the protective layer, ensuring long-lasting strength and functionality. You can also use an appropriate metal roofing paint to match the aesthetics. By adding this extra coat, your work will withstand the test of time. 

As you approach the final stages of your installation, it's crucial to focus on the finer details that guarantee the effectiveness and functionality of your flashing.

Step 5: Attention to Detail

Consider adding decorative metal elements strategically to reinforce critical areas such as the chimney's crown or the dormer's apex. 

Practical Design

Design your flashing layout with a practical mindset, ensuring water follows a smooth, efficient path. This will help prevent clogs and pooling throughout the drainage system.

Step 6: Battling the Elements 

With the installation complete, your flashing is ready to face any type of weather. Mother Nature tends to subject your roof to relentless rain, gusty winds, and blowing snow. To ensure its resilience, adopt a proactive maintenance approach, including regular inspections and timely repairs.

Preventive Maintenance

Similar to maintaining your home’s interior, you need to care for its exterior components too. Schedule professional roof inspections at least twice a year and keep your roof neat and clean. Swiftly replace any damaged roofing material and reapply sealants around the flashing to keep that protective barrier intact. You should also consider recoating your metal roof with weatherproof paint or a metal roof coating to prevent aesthetic and UV damage to the panels.

Let’s look into some dos and don’ts of installing metal roof flashing. These guidelines are essential to ensure your project is not just a success but will last for years to come.

Dos and Don'ts of Roof Flashing Installation

What to do:

metal roof flashing

Do Your Homework

Understand the unique traits of your roofing material and the climate it faces. Different materials thrive under different conditions. For instance, galvanized steel works well in rainy climates, while aluminum is resistant to the sun, protecting your home better than other options. Knowing these intricacies will guide your flashing choices.

Invest in Quality

When it comes to adding flashing to a metal roof, skimping on quality can lead to costly repairs or replacements. High-quality metal materials and precise tools are your allies, ensuring your flashing not only performs but offers protection for years.

Prioritize Safety

Safety should be your first priority during this project. One mistake can lead to accidents, roof damage, or frequent repairs. Dress for the occasion with proper safety gear, such as a harness, non-slip shoes, and use a secure ladder. And remember, never do roofing work alone, as a trusted partner can assist in case of an emergency.

Plan Ahead

Strategically plan your tasks, budget, and everything in between. This planning will ensure every piece falls into place without wasted materials or confusion during installation. Having a plan in place will also ensure the project is done on time, and correctly the first time.

Maintain Proper Slope

To maintain proper angles, make sure that your flashing components are tilted just right to guide water away. Having a proper slope is the key to avoiding puddles and leaks, and preserving your home for years.

Use Compatible Materials

Each part of your roof must blend seamlessly together. From the flashing itself to the fasteners and sealants, compatibility is your recipe for success. If one aspect does not align with the others, it can lead to lifting edges, leaks, and frequent repairs. 

Seek Professional Advice

If you are unsure at any point, feel free to seek guidance from a seasoned roofing professional. They can answer any questions, recommend materials, and offer solutions when you encounter obstacles.

What not to do:

Rushing In

Roof flashing installation shouldn’t be a race. Every move and step should be precise. Rushing through the job can result in mistakes that harm your roof and wallet. So, take your time, enjoy the process, and do right the first time.

Incorrect Overlapping

Think of your flashing as puzzle pieces. If you force them together the wrong way, you'll create gaps instead of a seamless system. Ensure that the flashing pieces efficiently channel water in the right direction.

Ignoring Local Building Codes

Now, this is the most important but most neglected part when it comes to DIY projects. As professionals, we follow the local building codes and regulations, and you should too. Not just because of the law but for your own safety, which is exactly why these codes are in place. Ignoring building codes can result in penalties or even the need to redo your installation.

Over-Tightening the Fasteners

You should make sure that the screws are securely placed, but not overly fastened. Over-tightening can damage materials and create unnecessary stress points, potentially leading to damage.

Improper Ventilation

Ensure that vents are integrated into your flashing design to maintain a healthy roofing system. Ventilation controls the temperature and moisture levels in the space below your roof, keeping your home comfortable and leak-free. 

By following these principles, you'll prepare your roof to stand strong against turbulent weather, leaks, and moisture problems. But remember, if you’re not handy with these types of projects, always consult your local roofing contractor for professional guidance.

If you are looking for metal roofing services in Pennsylvania, our experts will be happy to help you.

Get a Free Consultation on Metal Roofing Projects in Pennsylvania

At McClellands Contracting and Roofing, our expertise is just a click away. Our experts are ready to provide you with a free consultation on your metal roofing project in Pennsylvania. Whether it's selecting the right materials, installing flashing on your metal roof, or addressing any other roof concerns, we've got you covered. Like hundreds of homeowners, you can trust our skilled and experienced metal roofing experts. Call us at (412) 353-5660, and let us help you get started the right way!

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