5 Types of Roof Flashing Explained

Roof flashing is crucial in maintaining a watertight and structurally sound roofing system. It acts as a protective barrier, preventing water from seeping into vulnerable areas of the roof where leaks are likely to occur.

Properly installed flashing is indispensable in enhancing the longevity and functionality of your next roofing project. This article will explore roof flashing, its types, functions, installation methods, best practices and how to troubleshoot common issues.

What is Roof Flashing?

Roof flashing is a critical element in roofing systems that helps to prevent water infiltration and maintain a watertight seal. It is an essential weather-resistant material, typically made of metal or specialised waterproofing materials strategically installed at vulnerable points on the corrugated roofing to redirect water away from critical areas.

The purpose of roof flashing is to create a barrier that seals gaps and joints, ensuring that water does not seep into the structure of the metal roofing or the interior of the building.

Flashing is installed in areas where the roof is penetrated or interrupted, such as around chimneys, vents, skylights, valleys (where two roof planes meet) and ceiling edges. These are the most common areas where leaks are likely to occur, making flashing an essential component for protecting metal roofs against water damage.

The primary function of a common type of roof flashing is to direct water away from these vulnerable areas, channelling it toward the gutters or downspouts and preventing it from infiltrating the roof and causing potential leaks, decay or rot. It ensures that water flows off the top without seeping into the structure or causing damage to the roofing materials.

Types of Roof Flashing

Let’s take a look at the different types of roof flashing that are used in residential roofing.

1. Step Flashing

Contractors primarily use step flashing at intersections where the roof meets a vertical surface, such as a wall or dormer. It resembles a series of L-shaped metal pieces arranged in steps. Each piece is layered over the other during installation, creating a shingle-like effect. This design effectively channels water away from potential entry points, ensuring a tight seal and minimising the risk of leaks.

Step flashing is integrated with the roofing material and the vertical surface during installation, providing a secure barrier against water intrusion. People use it in roofing projects that involve asphalt shingles, cedar shakes, or other similar materials.

2. Chimney Flashing

Chimney flashing is vital for preventing water infiltration around the base of the chimney where it intersects with the roof. It typically involves two main components: the base flashing and the counterflashing. Install the base flashing on the top, weave it into the shingles, and embed the counterflashing into the roof space of the chimney’s mortar joints.

Properly installed chimney flashing creates a watertight seal, preventing water from seeping into the vulnerable areas around the chimney. Regular maintenance is crucial to ensure the effectiveness and longevity of chimney flashing.

3. Valley Flashing

Install valley flashing in the roof valleys or low points where two slopes meet. These areas are particularly susceptible to water accumulation and potential leaks. It is a specific design that channels water away from the valley, reducing the risk of water damage. It is commonly made of metal or specialised waterproofing materials to enhance durability.

Installation involves carefully fitting the valley flashing into the valley, ensuring a seamless and watertight connection. Proper placement of valley flashing is critical to maintaining the roofing system’s integrity.

4. Vent Pipe Flashing

We use vent pipe flashing to waterproof the areas around vent pipes that penetrate the roof. These pipes may be from plumbing, exhaust fans, windows or other systems. Vent pipe flashing includes a flexible base that conforms to the shape of the vent pipe and a metal flashing collar that fits over the ground and extends up the line.

Proper installation involves securely attaching the base to the apron, flashing the roof and fitting the metal collar tightly around the vent pipe. It creates a tight seal, preventing water from entering around the vent pipe penetration.

5. Drip Edge Flashing

Drip edge flashing is critical for safeguarding the edges and corners of your roof. Typically, install it along the roof’s perimeter, where the shingles meet the edge. Drip edge flashing prevents water from seeping into the underlying structure, safeguarding your roof’s decking and fascia.

During installation, the drip edge is positioned beneath the shingles and extends over the eaves, directing water away from the window fascia. Proper alignment and angling of drip edge flashing is essential for effective water diversion and protection.

Red flashing around a chimney

Best Practices for Roof Flashing Installation

Proper roof flashing installation is essential to prevent water leaks and ensure the longevity of your roofing system. Here are some best practices for roof flashing installation:

  • Use quality materials: Choose high-quality flashing materials compatible with your roofing material, such as metal (copper, aluminium or galvanised steel) or synthetic flashing materials like rubber or plastic.
  • Proper roof design: Ensure your roof has the slope and design to direct water away from vulnerable areas. Properly designed valleys and roof-to-wall connections can reduce the need for excessive flashing.
  • Install step flashing: For roofs that intersect with walls or chimneys, use step flashing. Install each piece of step flashing under the shingles, overlapping it with the next part to create a watertight barrier.
  • Counter-flash chimneys and vent pipes: Install counterflashing (cap flashing) around chimneys and vent pipes to prevent water from entering the gaps. Ensure adequate sealing of the counter-flashing to the masonry or roof.
  • Use kickout flashing: When a roof meets a sidewall, use kickout flashing to divert water away from the wall and into the gutter system. It helps prevent water from running down the wall and causing damage.
  • Seal joints and fasteners: Apply roofing cement or high-quality sealant to all joints, seams, and fasteners. It includes the intersections of flashing pieces and any nail penetrations. Make sure the adhesive is compatible with the flashing material.
  • Properly size flashing: Flashing should extend at least 10cm to 15cm (4 to 6 inches) up the vertical surface and at least 15cm (6 inches) onto the horizontal surface. The exact size may vary depending on the application and local building codes.
  • Flash roof penetrations: Any roof penetrations, such as vent pipes, skylights, or roof vents, should have proper flashing installed to prevent water infiltration. Use specialised flashing boots designed for these penetrations.
  • Install drip edge: Install a drip edge along the eaves and gables of your roof. It helps direct water into the gutters and prevents it from running down the fascia or into the attic.
  • Regular inspection and maintenance: Periodically inspect your roof flashing for wear, damage, or deterioration. Promptly repair or replace any damaged or compromised flashing to prevent leaks.
  • Hire a professional: Experienced roofing professionals are best suited for the challenging task of installing roof flashing. A qualified roofing contractor can ensure the correct flashing installation by being hired.
  • Follow local building codes: Always adhere to your local building codes and regulations when installing roof flashing. Codes vary by location, and compliance is crucial to ensure safety and prevent potential legal issues.

Adequately installed roof flashing is a critical component of a watertight roofing system. By following these best practices, you can have roof flashings help ensure your roof’s long-term performance and durability.

Common Roof Flashing Problems and Solutions

Despite its importance in preventing water infiltration, roof flashing can encounter various problems over time. These issues can arise due to aging, exposure to harsh weather conditions, poor installation, or inadequate maintenance. Here are some standard roof flashing problems and their respective solutions:

1. Leakage Around Flashing

Problem: One of the most frequent issues is water leakage around the flashing. It can occur due to gaps, cracks, or improper seals in the flashing material.

Solution: Professionals address the common problem of water leakage around flashing by conducting a thorough inspection to identify gaps, cracks, or inadequate seals in the flashing material. They then take precise measures to seal these vulnerable areas using appropriate sealants or flashing tape, ensuring a watertight and durable solution. This meticulous approach guarantees that the roof flashing functions effectively in preventing water infiltration and maintains the integrity of the roofing system.

2. Rust and Corrosion

Problem: Metal flashing can deteriorate over time due to rusting and corrosion, especially in regions with high humidity or frequent exposure to moisture.

Solution: Professionals address the issue of rust and corrosion in roof flashing by employing a two-pronged approach. Firstly, they identify and replace any severely rusted or corroded flashing components to ensure the structural integrity of the roof. Secondly, they apply specialised rust-resistant coatings to the remaining metal elements, safeguarding them against future deterioration. This proactive maintenance strategy helps extend the lifespan of the flashing and maintains the overall durability of the roofing system, particularly in moisture-prone areas.

3. Loose or Dislodged Flashing

Problem: High winds or improper installation can cause flashing to become loose, dislodged, or detached from its intended position.

Solution: Professionals address the issue of loose or dislodged roof flashing through a systematic approach. First, they carefully inspect the extent of the damage and assess whether the flashing can be reattached or if replacement is necessary. Using appropriate safety measures, they secure the loose flashing back in place with roofing cement or sealant, ensuring a watertight seal. If the flashing is severely damaged or corroded, they will replace it with new flashing material, custom-fitted to the roof’s unique configuration. This meticulous process ensures that the roof’s critical waterproofing system is fully restored and ready to withstand the elements.

Flashing around vent on roof.

4. Improper Sloping or Alignment

Problem: Flashing should have a proper slope to ensure adequate water runoff. Improper slope can cause water to accumulate, leading to leaks.

Solution: Professionals address the issue of improper sloping or alignment in roof flashing by carefully assessing the existing flashing and making necessary adjustments. They ensure that the flashing is correctly aligned to divert water away from vulnerable areas and create an appropriate slope to encourage effective water runoff. This proactive approach prevents water accumulation, ultimately safeguarding the roof from potential leaks and water damage.

5. Cracked or Brittle Flashing Material

Problem: Over time, flashing materials can become brittle, crack, or break, making many years ineffective in preventing water penetration.

Solution: Professionals address the issue of cracked or brittle flashing material by conducting a thorough inspection to identify the extent of the damage. Once the damaged sections are pinpointed, they carefully remove the old, ineffective flashing and replace it with new, durable flashing material. This ensures a watertight seal, preventing water penetration and safeguarding the integrity of the roof for years to come.

6. Improperly Sealed Joints

Problem: Inadequate sealing at joints or connections can lead to water seepage, especially in areas where two flashing pieces meet.

Solution: Professionals address the issue of improperly sealed joints in roof flashing by meticulously inspecting and identifying the weak points in the flashing system. They use high-quality sealants and specialised materials to seal the gaps and ensure a watertight connection, paying close attention to areas where two flashing pieces intersect. This meticulous approach helps prevent water seepage and enhances the overall durability of the roof’s flashing system, ensuring long-term protection against leaks and water damage.

7. Flashing Damage During Roof Repairs or Renovations

Problem: Roof repairs or renovations can inadvertently damage existing flashing, compromising its effectiveness.

Solution: Professionals address the issue of flashing damage during roof repairs or renovations by taking a systematic approach to ensure the integrity of the flashing. They carefully inspect the existing flashing before commencing any work and make necessary repairs or replacements as needed. Additionally, they exercise caution during the renovation process to minimise the risk of further damage. This proactive and meticulous approach helps maintain the flashing’s effectiveness and ensures a watertight seal for the roof.

Regular inspections, timely repairs, and proper maintenance are crucial in preventing and addressing these typical roof flashing problems. If you need help with how to handle flashing issues, it’s advisable to consult with a professional roofing contractor for expert guidance and assistance.

The Crucial Role of Roof Flashing Maintenance

Roof flashing plays a crucial role in maintaining the integrity and longevity of your roofing system by effectively redirecting water away from vulnerable areas.

It prevents leaks and water damage that could be costly to repair. Invest in quality materials, employ proper installation techniques, and conduct regular maintenance to ensure your roof flashing serves its purpose effectively.

Please note: This information is provided for advice purposes only. Regulations differ from state to state, so please consult your local authorities or an industry professional before proceeding with any work. See our Terms & Conditions here.

Last Edited on: 14th November 2023