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Understanding Metal Roof Flashing Types

When it comes to ensuring the longevity and durability of your metal roof, flashing plays a critical role. Metal roof flashing, an essential component of any roofing system, helps prevent water infiltration and protects vulnerable areas from damage. There are various types of metal roof flashing, each designed to address specific roofing challenges and enhance the overall performance of your roof.

In this article, I will explore the different types of metal roof flashing, their unique applications, and why choosing the right type is vital for maintaining a secure and watertight roofing system. Whether you’re a homeowner considering a new metal roof or seeking to upgrade your existing one, understanding these flashing types will equip you with the knowledge to make informed decisions and ensure your roof stands the test of time.

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Various Metal Roof Flashing Types

What’s the Difference Between Step Flashing and Counter Flashing?

What is the Difference Between end Flashing and Wall Flashing?

Is Counter Flashing Necessary?

Should Step Flashing be Nailed?

How to Flash Metal Roof to Wall

Various Metal Roof Flashing Types

Drip Edge Flashing… Installed along the roof’s edge where it meets the fascia board, diverting water away from the siding to prevent rot.

Step Flashing… Used around walls and vertical surfaces intersecting the roof. Made of individual metal pieces bent into a step shape for overlapping and creating a watertight seal.

Valley Flashing… Installed in the valleys where two roof slopes meet. Requires waterproof material like galvanized steel or copper.

Counter Flashing… Installed on top of valley flashing and up the sidewalls, preventing water from blowing under the valley flashing.

Base Flashing… Installed around chimneys and other roof penetrations. Needs a flexible material like lead or copper to conform to irregular shapes.

Cap Flashing… Used to cover the top of a wall where it meets the roof, preventing water from running down the wall and into the roof.

The best type of flashing for your metal roof depends on the specific application. A qualified roofing contractor can advise on the most suitable option for your needs. You may find this article helpful too. Metal Roof Trim Types and Their Uses

What’s the Difference Between Step Flashing and Counter Flashing?

Step flashing and counter flashing work together to ensure a watertight seal on your metal roof, but they serve different purposes:

Step Flashing… This is the primary layer of flashing and is installed in a series of overlapping pieces that “step” up the wall alongside the shingles. It channels water flowing down the roof over the top of each “step” and directs it towards the gutters.  Imagine shingles on the roof like tiles, and step flashing like a series of trays catching water overflowing from each shingle.

Step flashing is like the foot soldier in the war against water infiltration on your roof. It’s the first line of defense, made up of overlapping metal pieces that channel water flowing down the roof away from the wall and towards the gutters. Imagine a series of trays catching water overflowing from each shingle.

Counter Flashing… This acts as a secondary layer of protection and is typically installed on top of the step flashing. It goes over the top edge of the step flashing and often gets slipped underneath siding material (like vinyl) to create a double barrier against water intrusion.  Think of counter flashing as an extra layer of security, like a lid on top of those trays catching water.

Counter flashing, on the other hand, is like a secret agent. It works behind the scenes, often hidden under siding, to provide an extra layer of security. It goes over the top edge of the step flashing, creating a double barrier against water. Think of it as a lid on top of those trays catching water, ensuring no leaks even if some water sneaks past the first layer.

Step flashing is more visible and crucial for proper water drainage, while counter flashing offers additional peace of mind and protection in vulnerable areas.

What is the Difference Between end Flashing and Wall Flashing?

Both end flashing and wall flashing are important components of a metal roof system for preventing water infiltration, but they target different areas:

End Flashing… This type of flashing is specifically designed for the point where the sloping roof plane meets a vertical wall, like the gable end of a house. It acts like a metal shield that directs water flowing down the roof plane to divert away from the wall and into the gutter system. Imagine a metal sheet bent at an angle, forming a barrier between the roof and the wall.

Wall Flashing… This is a more general term encompassing various flashing types used around walls that intersect the roof. It can include step flashing (discussed previously) which channels water down the wall itself, but also flashing for features like windows or chimneys that penetrate the wall and could be potential leak points. Wall flashing provides a watertight seal between the roof and various wall elements.

Here’s a breakdown to highlight the key differences:

Location… End flashing – specifically for the roof-to-wall joint at the end of the slope. Wall flashing – used for various wall features that intersect the roof.

Function… End flashing – diverts water away from the wall. Wall flashing – creates a watertight seal between roof and wall elements.

Appearance… End flashing – often more visible as it forms a distinct barrier at the end of the roof. Wall flashing – can be visible (like step flashing) or hidden depending on the specific application.

In short, end flashing is a specialized type of wall flashing focused on the roof’s end, while wall flashing is a broader category encompassing different flashing types used for various wall features that meet the roof.

Is Counter Flashing Necessary?

Counter flashing is not absolutely necessary in all situations, but it provides additional benefits and is recommended in certain cases:

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High wind-driven rain… If you live in an area that experiences frequent or strong wind-driven rain, counter flashing can be crucial. The extra layer of protection helps prevent water from being blown up under the step flashing and infiltrating the roof.

Complex roof features… Roofs with features like valleys, skylights, or chimneys can have more vulnerable areas where water might pool or seep back under the shingles. Counter flashing provides an extra layer of security in these areas.

Local building codes… Some building codes may require counter flashing in certain situations. It’s always best to consult with a qualified roofing contractor to ensure your roof meets all code requirements.

Peace of mind… Even if your roof doesn’t strictly require counter flashing, it can offer peace of mind by providing an extra layer of protection against water leaks.

So, while not always mandatory, counter flashing can be a valuable addition to your metal roof, especially in areas with challenging weather conditions or complex roof designs.

Should Step Flashing be Nailed?

Yes, step flashing should be nailed during installation.

Here’s why nails are important for step flashing:

Secures the flashing… Nails hold the step flashing firmly in place, preventing it from moving or blowing off in high winds. This ensures the flashing stays positioned correctly to channel water effectively.

Creates a watertight seal… Nails help press the step flashing against the roof deck and underlying layers, creating a tighter seal and reducing the chance of water leaking behind the flashing.

Maintains proper positioning… Over time, temperature fluctuations can cause the metal flashing to expand and contract. Nails help the flashing maintain its intended position and prevent it from warping or lifting away from the roof deck.

However, there are some key points to remember about nailing step flashing:

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Nail placement… Nails are typically driven into the roof deck, not the wall itself. Nailing the flashing to the wall can create holes that could be potential leak points.

Nail quantity… Usually, one or two nails are used per piece of step flashing, strategically placed to secure it firmly without compromising the integrity of the material.

Nail type… Roofing nails with adequate length and corrosion resistance are recommended for this application.

Following proper installation techniques, including using the right nails and placement, ensures your step flashing functions effectively and protects your roof from water infiltration.

How to Flash Metal Roof to Wall

Flashing a metal roof to a wall is a crucial step to prevent water leaks and ensure the longevity of your roof. Here’s a general guide on the process, but remember it’s always recommended to consult a qualified roofing professional for proper installation:


– Step flashing (made from galvanized steel, aluminum, or copper)

– Counter flashing (optional, but recommended in some cases)

– Sheet metal shears or snips

– Roofing nails

– Caulk (optional, for additional sealing)


– Measure and Cut the Step Flashing: Measure the length of the wall where the roof meets it. Cut the step flashing pieces to the desired length using sheet metal shears or snips. Each piece should be slightly longer than the wall height and bent at a 90-degree angle at the top to create a flange that will lie flat against the wall.

– Install the Step Flashing: Slide the bottom edge of the first step flashing piece under the roofing panel.  Fold the flange created in step 1 over the wall. Nail the step flashing securely to the roof deck along the top edge, ensuring the nails don’t penetrate the wall. Overlap subsequent step flashing pieces by a few inches (as recommended by the manufacturer) and continue sliding them under the roofing panels and nailing them to the deck.

– Install Counter Flashing (Optional): If using counter flashing, it’s typically installed on top of the step flashing and up the sidewall. Overlap the counter flashing over the top edge of the step flashing and fold a flange along the bottom edge to slide under the siding material (if applicable).  Nail or screw the counter flashing securely in place.

– Seal the Joints (Optional): Apply a bead of roofing caulk along the top edge of the step flashing where it meets the wall for extra protection against water infiltration. You can also consider caulking the seams between overlapping flashing pieces.

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Important Notes:

– This is a general guide, and specific installation techniques may vary depending on the type of metal roofing, flashing material, and local building codes.

– Always refer to the manufacturer’s instructions for your specific flashing material and follow recommended installation practices.

– Working on a roof can be dangerous. If you are not comfortable performing this task yourself, it’s best to hire a qualified roofing contractor to ensure the flashing is installed correctly and safely.

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