How To Install Metal Roof Transition Flashing – Do-It-Yourself

It’s a sunny afternoon, and you’re standing in your backyard, admiring the sturdiness and sleekness of your brand-new metal roof.

But as you look closer, you notice the gaps and seams where different roof sections meet. Water could easily find its way in, potentially causing expensive damage to your home.

Transition flashing is a crucial element that ensures a watertight seal and a seamless finish when joining different sections of your metal roof.

In this step-by-step guide, I will walk you through the process of installing metal roof transition flashing, empowering you to protect your home with confidence and save on costly professional installation.

Installing Metal Roof Transition Flashing – How It Is Done

Installing transition flashing on a metal roof is crucial for ensuring proper water shedding and protection. Follow this step-by-step guide to measure, cut, install, and overlap transition flashing, safeguarding your roof from potential water damage.

StepsEstimated Required Time
Measure and Cut the Flashing30 minutes
Mark the Location of the Flashing10 minutes
Pre-Drill Screw Holes20 minutes
Install the Transition Trim and Overlap60 minutes

Step 1: Measure and Cut the Flashing

  • Measure the width of the area where the flashing will be installed using a measuring tape.
  • Start from one side and extend the tape measure to the other side, ensuring it is taut and straight.
  • Measure the height of the area where the flashing will be installed. Position the tape measure vertically, starting from the bottom edge and extending it to the top edge.
  • Place the flashing on a flat surface and use a pencil to mark the width and height measurements on the flashing directly. 
  • Choose a saw suitable for the type of flashing material you work with. For metal flashing, tin snips or metal shears are commonly used.
  • Align the flashing material along a straight edge or clamp it securely to prevent movement during cutting.
  • Cut the flashing along the marked lines using the saw.
  • After cutting, inspect the flashing to ensure it matches the required measurements and shape.
  • Verify that it extends at least 6 inches beyond the roof’s edge. This overhang is crucial for proper water shedding and protection.
  • Clean up any sharp edges or burrs on the cut edges of the flashing using a file or sandpaper.

Required Tools

  • Measuring tape
  • Pencil
  • Saw
  • File or sandpaper

Step 2: Mark the Location of the Flashing

  • Place the trim correctly on the roof where you intend to install the flashing.
  • Ensure it is properly aligned and positioned according to the desired layout and design.
  • Take a measuring tape and measure 1 ½ inches inward from the edge of the trim on both sides.
  • Mark these points using a pencil. These marks will serve as guidelines for the placement of the flashing.
  • If pre-drilling is required to install the flashing, mark the locations where your screws will fall.
  • This step is crucial if you are working with panels that have high seams. The high seams are the raised ridges on the panels where the screws will be inserted.

Required Tools

  • Measuring tape
  • Pencil

Step 3: Pre-Drill Screw Holes

  • Ensure the drill bit is suitable for the type of material you are working with, such as metal or wood.
  • Align your drill with the marked high seams of your panel. These marks indicate the positions where the screws will be inserted to secure the flashing.
  • Make sure the drill is perpendicular to the roof surface.
  • Begin pre-drilling your screw holes by applying gentle pressure on the drill and starting the rotation.
  • Slowly drill through the marked high seams, ensuring the drill bit penetrates the roofing material and creates a clean hole.
  • Repeat this process for each marked high seam along the panel, spacing the screw holes approximately 12 inches apart, center to center.
  • Move to the edge of the top section of the trim. Mark a point 1 inch inside and 2 inches from the edge on both sides of the trim.
  • These marks indicate where you will pre-drill holes to secure the trim’s top section.
  • Drill through the trim material, creating clean holes that will allow for the secure fastening of the trim.

Required Tools

  • Drill
  • Drill bit
  • Measuring tape
  • Pencil

Step 4: Install the Transition Trim and Overlap

  • If overlaps are needed, ensure that the last 12 inches of the overlap section are left without screws until the overlap is completed.
  • This allows for easier adjustment and alignment during the installation process.
  • Before fastening the pitch break trim, apply silicone sealant on top of the foam closures.
  • The silicone sealant helps create a watertight seal and prevents water from seeping under the trim.
  • Align your panel with the transition trim, ensuring that the pre-drilled holes on the panel align with the high seams of the corrugated metal roofing.
  • This alignment is important to ensure secure attachment and proper trim positioning.
  • Secure the panel in place by inserting two pancake screws on each end of the top section of the trim.
  • These screws will anchor the panel to the trim, providing stability and preventing movement.
  • Use lap screws and a sealing washer to attach the transition trim to your panel in the pre-drilled holes.
  • The lap screws are designed to attach the trim to the panel securely.
  • Ensure that the screws penetrate the high seam of the roofing panel and the foam closure underneath for a secure and watertight installation.
  • If an overlap is required, follow these additional steps:
  • Mark the edge of your trim at least 6 inches from the end.
  • Slightly pry open the hem of the trim up to the 6-inch mark using a suitable tool.
  • Cut a 6-inch notch in the hem using metal cutting snips.
  • Pry open the hem of the adjacent piece up to 6 inches inward.
  • Apply two lines of silicone sealant on the underside of the overlap section.
  • Connect the two sections by pushing the upper section upwards into position to prevent smearing the silicone sealant.
  • Finally, secure the top section of the trim by inserting pancake screws spaced 12 inches apart and positioned 2 inches from the top edge.

Required Tools

  • Silicone sealant
  • Foam closures
  • Measuring tape
  • Pencil
  • Screwdriver
  • Pancake screws
  • Lap screws with sealing washers
  • Metal cutting snips

How To Install Foam Closures For Transition Flashing?

Ensure a secure and watertight seal for your transition flashing by following these steps to install foam closures properly. This guide will walk you through the process for a professional and effective installation, from preparation to application.

StepsEstimated Required Time
Measure and Cut the Flashing40 minutes
Mark the Location of the Flashing10 minutes
Pre-Drill Screw Holes30 minutes
Install the Transition Trim and Overlap90 minutes

Step 1: Prepare the Roofing Underlayment

  • Begin by gathering the necessary materials, including an 8″ strip of roofing underlayment and double-sided butyl tape.
  • Lay out the roofing underlayment along the roof’s edge where the transition flashing will be installed.
  • The underlayment acts as a protective barrier and helps prevent water penetration.
  • Take the double-sided butyl tape and carefully position it at the edge of the roofing underlayment.
  • The tape should be applied parallel to the edge, ensuring complete coverage.
  • Slowly unroll the tape, pressing it firmly onto the underlayment surface. Make sure the tape adheres securely and creates a strong bond.
  • Eliminate any air bubbles or creases that may have developed during application. This ensures a flat and even surface for the foam closures.
  • Double-check the alignment and positioning of the butyl tape, ensuring it extends along the entire length of the underlayment strip. This will provide consistent waterproofing and adhesion.

Step 2: Layout and Align the Roofing Panels

  • Begin by gathering the roofing panels that will be installed in the top section of the transition flashing.
  • Ensure that you have the correct number of panels for the desired coverage.
  • Lay out the panels on a flat surface near the installation area. This will allow you to easily assess their alignment and make any necessary adjustments before securing them in place.
  • Carefully position the panels to ensure they are squared and aligned with the lower section of the corrugated roofing panels.
  • The corrugations are the raised ridges or waves that run horizontally across the panels.
  • Pay close attention to the orientation of the corrugations on both the top and lower sections of the roofing panels.
  • They should line up seamlessly, creating a consistent and visually pleasing transition.
  • Measure the distance from the edge of each panel to the adjacent panels to ensure they are evenly spaced.
  • Make any necessary adjustments by shifting or rotating the panels until they are perfectly squared and aligned.
  • Once you are satisfied with the layout and alignment, carefully transfer the panels from the flat surface to the installation area.
  • Remember to maintain their positioning and alignment during the transfer.

Step 3: Install the Foam Closures

  • Take the foam closures and position them on top of the butyl tape previously applied at the edge of the 8″ roofing underlayment.
  • The butyl tape acts as an adhesive and helps to create a strong bond between the closures and the underlayment.
  • Align the foam closures with the corrugations of the roofing panel.
  • It is crucial to ensure that the foam closures are aligned properly with the corrugations for a snug fit and effective sealing.
  • Carefully press down on the foam closures to secure them in place. Apply even pressure along the length of each closure to ensure proper adhesion to the butyl tape and underlayment.
  • Double-check the foam closures’ alignment with the roofing panel’s corrugations. Make any necessary adjustments to ensure they are properly positioned.
  • Verify that the foam closures are securely attached and provide a tight seal against the roofing panel. This will help to prevent water infiltration and enhance the overall performance of the transition flashing.
  • If required, repeat this process for each foam closure along the length of the transition flashing, ensuring consistent alignment with the corrugations.
  • Applying a bead of silicone sealant is recommended on top of the foam closures. This additional sealant layer will provide an extra barrier against water penetration and reinforce the seal.

Step 4: Mark and Align for Screw Placement

  • Place a measuring tape along each side of the roofing panel, starting from the edge.
  • Measure 1 ½ inches inward from the edge and make a mark with a pencil on both sides. These marks will serve as reference points for the screw placement.
  • Once the marks are made, double-check their accuracy to ensure they are evenly spaced and aligned on both sides of the panels.
  • To create a clear guide for screw placement, snap a chalk line by stretching a taut line between the marked points on each side of the roofing panels.
  • Ensure that the chalk line aligns with the foam closures and runs parallel to the corrugations of the roofing panels. This alignment is crucial to maintain consistency and provide structural integrity to the installation.
  • Once the chalk line is snapped, visually inspect it to verify its straightness and alignment.

Step 5: Apply Silicone Sealant

  • Before installing the roofing panels, inspect the foam closures and ensure they are clean and debris-free.
  • Remove any dirt or particles that may interfere with the adhesion of the sealant.
  • Take a tube of silicone sealant suitable for roofing applications. Cut the tube tip at a 45-degree angle to create a small opening for the sealant to flow through.
  • Squeeze a generous bead of silicone sealant onto the foam closures.
  • Start at one end of the closure and continue along its length, applying an even and consistent line of sealant.
  • Use a caulking gun or your finger to spread and smooth the sealant along the foam closures. Ensure that the sealant covers the entire width and length of the closures, creating a complete seal.
  • Pay special attention to the edges and corners of the closures, as these areas are prone to potential water entry points.
  • Allow the silicone sealant to dry and cure. This typically takes several hours.

Metal Roof Flashing Types – Uses & Benefits

Discover the essential types of metal roof flashing, including step flashing, apron flashing, counter flashing, valley flashing, drip edge, and kickout flashing, each serving a unique purpose in protecting your roof and preventing water damage.

Step Flashing

Step flashing is commonly used in roofing systems to provide a watertight seal and protect against water infiltration.

Its installation involves positioning the individual metal pieces in a step-like pattern, with each piece overlapping the one beneath it.

This overlapping design effectively channels water away from the intersection of the roof and vertical surface.

The 90-degree angle at which the step flashing is bent ensures that water is directed downward and away from the joint.

This prevents water from seeping into the building structure and causing damage, such as rot, mold growth, or structural deterioration.

Step flashing is particularly useful in areas where the roof meets walls, chimneys, or dormers.

These areas are prone to water intrusion due to the potential for rain or snow driven by wind against the vertical surface.

Step flashing effectively diverts water away and prevents it from entering the building envelope by providing a continuous barrier.

One of the key benefits of step flashing is its individual and replaceable nature. If a section of flashing becomes damaged or deteriorated over time, it can be easily removed and replaced without affecting the surrounding flashing components.

This makes maintenance and repairs more straightforward and cost-effective.

Step flashing works with other roofing materials, such as shingles or siding, when properly installed to create a reliable and durable waterproofing system.

It ensures that water is effectively managed and directed away from vulnerable areas, safeguarding the integrity of the roof and the structure beneath it.

Apron Flashing

Apron flashing is an important component of roofing systems, particularly at the base of a roof where it meets a vertical surface such as a wall.

It is a continuous strip of metal flashing that is installed horizontally to provide protection and redirect water away from the foundation of a building.

The primary purpose of apron flashing is to prevent water from infiltrating the foundation, which can lead to moisture-related issues, such as basement leaks, foundation damage, and mold growth.

By directing water away from the foundation, apron flashing helps maintain the structural integrity of the building and safeguards against costly water damage repairs.

Apron flashing is typically made of durable materials like aluminum or copper. These materials are chosen for their resistance to corrosion and longevity, ensuring that the flashing can effectively perform its protective function for an extended period.

Additionally, aluminum and copper are malleable metals, allowing for easy installation and customization to fit the specific dimensions and contours of the roofing system.

During installation, apron flashing is securely fastened to the base of the roof and overlaps with the roofing material above it.

This overlap creates a watertight seal that prevents water from seeping between the flashing and the roofing material, further enhancing its effectiveness.

In addition to its functional benefits, apron flashing also contributes to the aesthetic appeal of the roofline.

It provides a clean and finished look to the transition between the roof and the vertical surface, improving the overall appearance of the building’s exterior.

Counter Flashing

Counter flashing is an integral component of a roofing system, working in conjunction with apron flashing to provide enhanced protection against water infiltration.

It is installed on top of a vertical surface, such as a wall, chimney, or parapet, and overlaps the base of the roofing material and the underlying apron flashing.

The primary purpose of counter flashing is to create a watertight seal and reinforce the integrity of the flashing system.

By overlapping the base of the roofing material and the apron flashing, counter flashing acts as a barrier against water penetration in vulnerable areas.

Counter flashing is typically fabricated from the same material as the roofing material, ensuring compatibility and a seamless appearance.

Common materials used for counter flashing include aluminum, copper, or galvanized steel. These materials offer excellent durability, resistance to corrosion, and longevity, allowing the counter flashing to withstand the elements and provide long-term protection.

During installation, the counter flashing is carefully fitted and secured on top of the vertical surface, ensuring a tight fit and proper overlap with the roofing material and apron flashing.

This overlap creates a robust seal, minimizing the risk of water intrusion and reinforcing the overall waterproofing of the roofing system.

When properly installed, it provides a clean and professional finish to the transition between the vertical surface and the roofing material, enhancing the overall visual appearance of the structure.

Valley Flashing

Valley flashing is a critical component of roofing systems designed to manage water runoff and prevent leaks in the valleys where two sloping roof sections meet.

It is typically in the form of a U-shaped metal flashing that follows the contour of the valley.

The primary purpose of valley flashing is to channel water down the roof and away from the valley, directing it toward the gutters or eaves.

By effectively managing water flow, valley flashing helps prevent water from pooling in the valley, which can lead to leaks and water damage.

Valley flashing is commonly made of materials like aluminum or copper due to its corrosion resistance and durability.

These metals can withstand exposure to the elements and provide long-lasting protection.

Aluminum is lightweight and easily malleable, making it easier to work with during installation. On the other hand, copper offers exceptional longevity and aesthetic appeal and can develop a natural patina over time.

During installation, valley flashing is carefully positioned and secured in the valley, following the contour of the roof.

It is typically installed underneath the roofing material, such as shingles or tiles, and overlaps with adjacent sections of valley flashing.

Proper installation of valley flashing is crucial to its effectiveness. It should be securely fastened to the roof deck or underlying substrate, ensuring a tight fit and proper alignment with the roof sections.

Additionally, you can apply sealants or adhesives to enhance the watertight seal and provide additional protection against leaks.

By effectively directing water away from the valley, valley flashing plays a vital role in maintaining the roofing system’s integrity. It helps prevent water accumulation, which can lead to rot, mold, and other water-related issues.

Drip Edge

A drip edge is a crucial component of a roofing system that is installed along the eaves of a roof, extending beyond the edge.

Its main purpose is to manage water runoff and prevent potential damage to the building’s structure, siding, and foundation.

The primary function of a drip edge is to guide water away from the roof edge. Extending beyond the roof’s edge creates a small gap or overhang that directs water into the gutters or away from the building.

This prevents water from dripping down the sides of the house, which can lead to moisture damage, rot, and erosion of the foundation.

Drip edge is typically made of durable and weather-resistant aluminum or copper.

During installation, the drip edge is positioned along the roof’s eaves, with one edge overlapping the roof deck and the other extending beyond the roof edge.

It is typically fastened to the roof deck using nails or screws, ensuring a secure and stable attachment.

The drip age helps to protect the underlying roofing materials by preventing water from seeping underneath and causing damage.

It can also help to prevent the entry of small pests, such as insects and rodents, into the roof structure.

A properly installed drip edge is essential to a well-designed roofing system. It helps to maintain the integrity of the roof, prevents water-related damage, and contributes to the overall longevity of the structure.

Regular inspection and maintenance of the drip edge are essential to ensure its effectiveness.

Kickout Flashing

Kickout flashing is a crucial component of a roofing system that is specifically designed to address water diversion and prevent water damage at the intersection of a roof slope and a sidewall.

It is vital in directing water away from the wall and into the gutter system, effectively managing water runoff and protecting the building from potential leaks and water-related issues.

The primary function of kickout flashing is to redirect water that flows down the roof slope away from the sidewall.

Without kickout flashing, water can easily get trapped or back up under the roofing material, leading to water infiltration.

By providing a strategic redirection point, kickout flashing ensures that water is efficiently channeled into the gutter system, preventing it from causing harm to the underlying structure.

Kickout flashing is typically installed at the lower end of the roof slope, where it meets a sidewall, forming a triangular shape.

It is positioned in such a way that it overlaps the roofing material and extends outward, creating a barrier that directs water away from the wall.

The flashing is integrated with the sidewall and securely attached to provide a watertight seal and prevent water from seeping behind it.

Kickout flashing is commonly made of materials like aluminum or copper to ensure durability and resistance to the elements.

Proper installation of kickout flashing is essential to its effectiveness. It should be seamlessly integrated with the roofing material and sidewall, creating a smooth transition and a reliable barrier against water intrusion.

Checking for any damage or blockages is essential to ensure optimal performance.

Bottom Line

Congratulations! You’ve reached the end of our guide on installing metal roof transition flashing.

This journey has empowered you with the knowledge and confidence to tackle this critical task independently.

Remember, the transition areas of your roof are critical points where water infiltration can occur if not adequately protected.

With the installation of metal roof transition flashing, you’ve taken a proactive step in safeguarding your home from potential leaks and costly damages.

Not only have you added a functional element to your roofing system, but you’ve also enhanced the visual appeal of your metal roof.


What is roof transition flashing?

Roof transition flashing is a strong defense against leaks at the junction where two distinct roof pitches converge. Sealing the lower side of the flashing using outside closures is essential, while inside closures can secure it underneath the upper panels. Moreover, gambrel flashing is a comparable solution when the lower pitch exhibits a steeper incline than the upper pitch.

How Much Does Transition Flashing Cost?

The cost of transition flashing varies based on factors such as the gauge of the flashing and the type of paint finish. On average, you can expect transition flashing to range from $1.50 to $2.50 per linear foot.

What type of flashing is best?

  1. Copper Flashing: Copper is considered the highest quality option for flashing. It offers excellent durability, corrosion resistance, and an attractive appearance that develops a natural patina. However, copper flashing tends to be more expensive compared to other materials.
  1. Aluminum Flashing: Aluminum is a popular choice for flashing due to its affordability and decent durability. It is lightweight, resistant to corrosion, and formed to fit various roof configurations. Aluminum flashing provides a good balance between quality and cost-effectiveness.

Flashing Membrane: Flashing membranes, such as synthetic materials like PVC or rubberized asphalt, are budget-friendly options for flashing repairs. You can use flashing membranes for temporary fixes or when the cost is significant.