close up to roof flashing against blue sky

Posted On: September 14, 2023

A Homeowner’s Guide to Understanding Roof Flashing

Your roof is the first line of defense against the elements, shielding your home from rain, snow, and other weather conditions. While the shingles are vital for preventing water from seeping into your home, there’s another unsung hero that plays a crucial role in keeping your roof watertight— roof flashing.

In this article, we will explore:

  • What roof flashing is
  • What it’s made of
  • Signs that indicate it’s time to replace your roof flashing
  • Types of roof flashing

What Is Roof Flashing?

red tile roof and flashing on chimney

Roof flashing is a weather-resistant material installed on the joints and transitions of your roof to prevent water from penetrating vulnerable areas. It is typically made of metal, although other materials like rubber, plastic, or composite materials are sometimes used. 

Flashing is applied at areas where the roof meets vertical surfaces like chimneys, skylights, dormer windows, vent pipes, and roof valleys. These areas are more susceptible to leaks and water damage, making roof flashing a critical component of a well-protected roofing system.

Types of Roof Flashing

Roof flashing comes in various types, each specifically designed to address different roof configurations and areas where water intrusion is most likely to occur. Understanding the different types of roof flashing can help you choose the best option for your roofing needs. Here are some common types of roof flashing:

1) Step Flashing

Step flashing is one of the most commonly used types of roof flashing. It is typically made of metal, such as aluminum or galvanized steel, and is installed along the sides of chimneys and dormer walls. Step flashing is designed to create a water-resistant barrier by overlapping the roofing material in a “step-like” pattern, allowing water to flow down the roof and away from the joint.

2) Chimney Flashing 

Chimney flashing is specifically designed to protect the area where the chimney intersects with the roof. It consists of two main components: base flashing and counterflashing. Base flashing is installed under the shingles and extends up the sides of the chimney, while counterflashing is embedded into the mortar joints of the chimney. Together, they create a waterproof seal around the chimney, preventing water from seeping into the roof.

3) Valley Flashing 

Valley flashing is used in roof valleys, where two roof slopes meet. Valleys are particularly vulnerable to water accumulation, so this type of flashing is crucial for directing water away from the joint. Valley flashing is often made of metal and runs down the center of the valley, overlapped by the roofing material on both sides.

4) Drip Edge Flashing

worker installing drip edge flashing on the roof

Drip edge flashing is installed along the edges of the roof to protect the roof decking and fascia from water damage. It helps to direct water away from the roof and into the gutters, preventing water from running down the fascia and causing rot. Drip edge flashing is available in various materials, including aluminum, galvanized steel, and PVC.

5) Vent Pipe Flashing

 Vent pipe flashing is used around vent pipes and other vertical protrusions on the roof, such as plumbing vents and exhaust pipes. It typically consists of a neoprene or rubber gasket that fits tightly around the pipe, ensuring a water-resistant seal. Some vent pipe flashings also have a metal base that provides additional protection.

6) Skylight Flashing

Skylight flashing is designed to seal the area around skylights, preventing water from infiltrating between the skylight and the roof. Skylight flashings vary depending on the type of skylight and the roof slope. Some skylights come with integrated flashing systems, while others require separate flashing kits.

7) Wall Flashing

Wall flashing is used at the junction between the roof and a vertical wall, such as a sidewall or parapet. It prevents water from seeping into the wall cavity and causing damage to the interior of the building. Wall flashing is typically made of metal and extends a few inches up the wall and over the roof surface.

8) Eave Flashing

Eave flashing, also known as gutter apron flashing, is installed along the eaves of the roof to protect the roof edge and the fascia from water damage. It ensures that water is directed into the gutters and away from the roof and the building’s foundation.

Materials Used for Roof Flashing

As mentioned earlier, the most common material used for roof flashing is metal. Aluminum and galvanized steel are popular choices due to their durability, rust resistance, and cost-effectiveness. Copper flashing, while more expensive, offers excellent corrosion resistance and can develop a beautiful patina over time, adding an aesthetic appeal to historic or high-end properties.

In recent years, synthetic materials like rubber and plastic have gained popularity for specific applications. Rubber flashing is flexible and can be molded to fit curved or irregular surfaces, making it suitable for round chimneys or domed skylights. Plastic flashing is lightweight and easy to handle, but it may not have the same longevity as metal or rubber.

Signs that It’s Time to Replace Roof Flashing

Roof flashing is designed to last for several years, but exposure to harsh weather conditions and temperature fluctuations can lead to wear and tear over time. Here are some signs that indicate it’s time to replace your roof flashing:

  • Visible Damage: Inspect the flashing regularly, and if you notice any signs of rust, corrosion, cracks, or dents, it’s a clear indication that it needs replacement.
  • Water Stains: Water stains on your ceiling or walls can be a telltale sign of a leak caused by damaged flashing. Address this issue promptly to prevent further water damage to your home’s interior.
  • Missing Flashing: If you discover areas where flashing is entirely missing or improperly installed, you should have it replaced immediately to prevent potential leaks.
  • Loose Flashing: Flashing that has come loose from the roof or vertical surfaces can leave gaps for water to seep through. Address any loose flashing promptly to maintain a watertight seal.

Work with a Trusted Roofing Contractor

Your roof is a vital part of your home. Let Northface Construction help you keep it safe! We’ll install your roof flashing materials properly so that you can rest easy. Contact our friendly team members today to set up your first appointment!


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