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  • Writer's pictureD&G Exteriors

Roof Flashing: What It Is and Why It's Important

Roof flashing is an essential component of any building's roofing system. It is a thin material, usually made of sheet metal or plastic, that is installed around the roof's features such as chimneys, vents, and flue pipes. The primary purpose of roof flashing is to redirect water away from these critical areas of the roof, preventing water damage and leaks.


The importance of roof flashing cannot be overstated. Without proper flashing, water can seep into the roof's interior and cause significant damage to the structure. This damage can be costly to repair, and in some cases, it can even compromise the building's structural integrity. Therefore, it is crucial to ensure that the roof flashing is installed correctly and is in good condition.


Roof flashing is available in different materials, including copper, aluminum, and galvanized steel. Each material has its advantages and disadvantages, and the choice of material depends on various factors, such as the roof's slope, the climate, and the building's location. Regardless of the material used, proper installation is critical for the flashing to function correctly.


Types of Roof Flashing

Roof flashing is an essential component of any roofing system. It is designed to prevent water from penetrating the roof's surface and causing damage to the underlying structure. There are several types of roof flashing, each designed for a specific purpose. In this section, we will explore the most common types of roof flashing.


Step Flashing

Step flashing is a type of flashing that is used to seal the intersection between a sloped roof and a vertical wall. It is made from a variety of materials, including copper, aluminum, steel, galvanized steel, lead, zinc, plastic, and rubber. Step flashing is installed in a series of steps, with each piece overlapping the one below it. This creates a watertight seal that prevents water from penetrating the roof.


Counter Flashing

Counter flashing is a type of flashing that is used to cover the top edge of step flashing. It is installed on the vertical wall and overlaps the step flashing. Counter flashing is also made from a variety of materials, including copper, aluminum, steel, galvanized steel, lead, zinc, plastic, and rubber. It is designed to prevent water from seeping behind the step flashing and causing damage to the underlying structure.


Valley Flashing

Valley flashing is used to seal the intersection between two sloped roof surfaces. It is installed in the valley, which is the area where the two roof surfaces meet. Valley flashing is made from a variety of materials, including copper, aluminum, steel, galvanized steel, lead, zinc, plastic, and rubber. It is designed to prevent water from penetrating the roof in this vulnerable area.


Drip Edge Flashing

Drip edge flashing is installed along the edge of the roof to prevent water from flowing back under the roofing material. It is made from a variety of materials, including copper, aluminum, steel, galvanized steel, lead, zinc, plastic, and rubber.. This creates a small gap between the edge of the roof and the fascia board, allowing water to flow freely off the roof.


Base Flashing

Base flashing is installed around roof penetrations, such as chimneys and vents. It is designed to prevent water from seeping into the roof around these vulnerable areas. Base flashing is made from a variety of materials, including copper, aluminum, steel, galvanized steel, lead, zinc, plastic, and rubber. It is installed around the base of the penetration and overlaps the roofing material to create a watertight seal.


Installation and Repair

Installing New Flashing

Installing new flashing is a crucial part of any roofing project, whether it's a DIY project or handled by a professional. To install new flashing, one must first gather the necessary tools, including tin snips, a hammer, roofing cement, and sealant. Safety should always be a top priority, so it's important to wear protective gear such as gloves and goggles.


The first step in installing new flashing is to remove the old flashing and clean the area thoroughly. Then, measure and cut the new flashing to size using tin snips. Once the flashing is cut, it can be installed by nailing or screwing it in place and securing it with roofing cement or sealant to create a watertight seal.


Repair Flashing

It's important to repair flashing as soon as any damage is noticed to prevent further damage to the roof. To repair flashing, one must first identify the damaged area and clean it thoroughly. Then, measure and cut a piece of new flashing to size using tin snips.

Next, position the new flashing in place and secure it with nails or screws. To create a watertight seal, apply roofing cement or sealant around the edges of the flashing.


It's important to ensure that the flashing is properly secured and sealed to prevent any future leaks.


Re-roofing Job

If a re-roofing job is being done, it's important to inspect the flashing and replace any damaged or worn-out flashing. This will ensure that the new roof is properly protected and will prevent any future leaks.


During a re-roofing job, the old shingles and flashing will be removed, and the new flashing will be installed before the new shingles are put in place. It's important to hire a professional for a re-roofing job to ensure that the job is done correctly and safely.


Overall, proper installation, repair, and maintenance of flashing is crucial for the longevity and protection of any roof. Whether it's a DIY project or handled by a professional, safety should always be a top priority.


Common Flashing Concerns

Roof flashing is a vital component of any roofing system as it plays a crucial role in preventing water infiltration and damage. However, over time, flashing can develop issues that can compromise the integrity of the roof.


Here are some common flashing concerns that homeowners should be aware of:


Water Leaks and Damage

One of the most common flashing concerns is water leaks and damage. When flashing is not installed correctly or has become damaged, water can infiltrate the roof and cause significant damage. Water leaks can lead to mold growth, wood rot, and deck collapse if left untreated. Homeowners should inspect their flashing regularly for signs of water damage, such as water stains on the ceiling or walls.


Corrosion and Rust

Metal flashing is susceptible to corrosion and rust, especially in areas with high humidity or salt exposure. Corrosion and rust can compromise the structural integrity of the flashing and lead to water infiltration. Homeowners should inspect their flashing regularly for signs of corrosion and rust. If corrosion or rust is present, the flashing should be replaced immediately to prevent further damage.


Structural Compromises

Flashing is an essential component of the roof structure, and any compromise to its integrity can lead to significant structural issues. If flashing is not installed correctly or has become damaged, it can compromise the structural integrity of the roof and lead to deck collapse or other structural issues. Homeowners should inspect their flashing regularly for signs of structural compromise, such as gaps or cracks in the flashing.


To prevent these common flashing concerns, homeowners should schedule regular roof inspections and maintenance. A professional roofing contractor can identify potential flashing issues early and address them before they become more significant problems. By taking proactive measures to maintain their flashing, homeowners can ensure the longevity and integrity of their roofing system.


Flashing for Roof Features

Roof flashing is a critical component of any roofing system. It is installed to direct water away from critical areas of the roof where it meets a vertical surface like a wall or a dormer. The purpose of flashing is to prevent water from penetrating the roof and causing damage to the underlying structure.


Chimney Flashing

Chimney flashing is a type of flashing that is installed around the base of a chimney to prevent water from penetrating the roof. It is typically made of metal, such as aluminum or galvanized steel. Chimney flashing is installed in two parts: the base flashing and the counter flashing. The base flashing is installed under the shingles and up the side of the chimney, while the counter flashing is installed into the mortar joints of the chimney.


Vent Pipe Flashing

Plumbing vent pipes are installed to vent sewer gases out of the home. Vent pipe flashing is installed around the base of the vent pipe to prevent water from penetrating the roof. Vent pipe flashing is typically made of metal, such as aluminum or galvanized steel. It is installed in a similar way to chimney flashing, with a base flashing and a counter flashing.


Skylight Flashing

Skylight flashing is installed around the base of a skylight to prevent water from penetrating the roof. It is typically made of metal, such as aluminum or galvanized steel. Skylight flashing is installed in two parts: the base flashing and the step flashing. The base flashing is installed under the shingles and up the side of the skylight, while the step flashing is installed into the shingles on either side of the skylight.


Dormer and Valley Flashing

Dormer and valley flashing is installed in areas where two roof planes meet, such as at a dormer or in a valley. It is typically made of metal, such as aluminum or galvanized steel. Dormer and valley flashing is installed in a similar way to chimney flashing, with a base flashing and a counter flashing.


Overall, flashing is an essential component of any roofing system. Properly installed flashing will help prevent water from penetrating the roof and causing damage to the underlying structure.


Materials and Durability

Choosing the Right Materials

When it comes to choosing the right material for roof flashing, it is important to consider durability, malleability, and cost. The most commonly used materials for roof flashing are copper, aluminum, steel, galvanized steel, lead, and zinc. Each of these materials has its own unique properties that make it suitable for different applications.


Copper flashing is a popular choice due to its durability and malleability. It is highly resistant to corrosion and can withstand extreme weather conditions. Copper flashing is also easy to work with, making it a popular choice for both professionals and DIY enthusiasts.

Aluminum flashing is another popular choice due to its low cost and lightweight properties. It is easy to install and can be used in a variety of applications. However, aluminum flashing is not as durable as other materials and may not be suitable for areas with harsh weather conditions.


Steel flashing is a strong and durable option that can withstand extreme weather conditions. It is also resistant to corrosion and can last for many years. However, steel flashing is not as malleable as other materials and may not be suitable for complex flashing applications.

Galvanized steel flashing is a low-cost alternative to other materials. It is highly resistant to corrosion and can last for many years. However, galvanized steel flashing may not be suitable for areas with harsh weather conditions.


Lead flashing is a durable and malleable option that can be used in a variety of applications. It is highly resistant to corrosion and can last for many years. However, lead flashing is not as popular as other materials due to health concerns.


Zinc flashing is a durable and corrosion-resistant option that can last for many years. It is also malleable and can be used in a variety of applications. However, zinc flashing is not as popular as other materials due to its higher cost.


Ensuring Longevity

To ensure the longevity of roof flashing, it is important to choose the right material and install it properly. Proper installation includes ensuring the flashing is properly sealed and secured to the roof. It is also important to inspect the flashing regularly and make any necessary repairs or replacements.


In addition, it is important to choose a material that is suitable for the specific application. For example, copper flashing may be more suitable for areas with harsh weather conditions, while aluminum flashing may be more suitable for areas with mild weather conditions.


Overall, choosing the right material and ensuring proper installation can help ensure the longevity of roof flashing. By taking these steps, homeowners can protect their homes from water damage and other costly repairs.


Professional Roofing Insights

When to Call a Professional

Although it may be tempting to save money by fixing your own roof flashing, it is important to know when to call a professional. A professional roofer has the knowledge, experience, and equipment necessary to fix your roof flashing correctly and safely. Attempting to fix roof flashing on your own can lead to further damage to your roof and potentially dangerous situations.


If you notice any signs of roof flashing issues, such as water stains on your ceiling or walls, it is important to call a professional roofing contractor as soon as possible. Delaying repairs can lead to more extensive damage and higher repair costs.


Inspection and Maintenance

Regular inspection and maintenance are essential to keeping your roof flashing in good condition. A professional roofing contractor can inspect your roof for potential issues and provide maintenance services to prevent problems from occurring.


During an inspection, a professional roofer will check for signs of damage or wear and tear on your roof flashing. They will also look for potential issues, such as loose or missing flashing, and provide recommendations for repairs or replacement as needed.


In addition to professional inspections, it is important to perform regular maintenance on your roof flashing. This includes cleaning debris from your roof, checking for damage after storms, and ensuring that your roof flashing is properly sealed.


By following these tips and working with a professional roofing contractor, you can ensure that your roof flashing is in good condition and protect your home from potential issues.

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