What Is Roof Flashing? (2024 Roofing Guide)

It can seem like a roof is made only of the asphalt shingles, metal panels, wooden shakes, or clay tiles that are visible from the surface. However, there’s actually a lot more going on with roof layers than meets the eye. Underneath this top layer of roofing, there are multiple layers of materials that protect your home, such as:

  • The wooden roof deck
  • Your underlayment
  • A water-shielding layer
  • And more!

One of the most important pieces of this multi-layer structure is your roof flashing. But what is roof flashing, and why do you need it? Here, we answer both these questions and more.

What Does Roof Flashing Do?

roof flashing on house tile roof

Roof flashing is a thin piece of metal aligned along the edge of your roofing material. It’s usually installed anywhere one plane of your roof meets another surface. This includes anywhere one edge of your roof meets another edge of the roof, as well as where the roof meets the edges of roof features like chimneys, skylights, and vents.

This metal flashing provides a waterproof seal for your roof, keeping moisture on the shingles, shakes, or metal panels and away from the underlayers of the roof.

Types of Roof Flashing

There are several common types of roof flashing, each named for its specific purpose:

  • Apron flashing, or continuous flashing: Long, “continuous” pieces of flashing that run along a roof edge. They’re not very flexible and can have a difficult time keeping up with regular expansion and contraction of your roof throughout the year. This makes them susceptible to damage in the long run.
  • Counter flashing: Works with base flashing (listed below) to provide extra protection in certain areas of your roof. This technique is often used with chimneys, where one piece of flashing is laid along the base of the chimney, and then the second is attached to the brick itself.
  • Valley flashing: Roof valleys are the parts of the roof where two sides of the roofing meet at a low point and create an interior angle. The edge where they meet is covered with valley flashing that runs all the way to the gutter at the bottom edge of both sides of the roof.
  • Step flashing: Installed a row at a time along with the shingles, usually where the sides of your roof meet vertical walls. It’s meant to keep water from dripping between the edge of the row of shingles and the wall right next to it. It can be very time-consuming to install.
  • Vent pipe flashing: Exactly as the name suggests, this cylindrical type of roof flashing goes around the vents in your roof. The flashing is installed first, and then the shingles or other roofing materials are laid on top of the base of the flashing to create a watertight seal.
  • Drip edge flashing: This goes along the very bottom edge of the roof and works in tandem with your gutter system to carry water away from the edge of your home and out through your downspouts.
  • Base flashing: A piece of flashing that goes underneath another layer of flashing, called counter flashing (listed above). This double layering provides extra waterproofing to the area.
  • Skylight flashing: Flashing that goes around a skylight. Sometimes the skylight itself comes with flashing, but sometimes it must be purchased and installed separately.

How Is Roofing Flashing Installed?

construction worker installing roof flashing on chimney

Flashing installation must be done by a professional roofer, as they know all the building codes, permit requirements, and safety considerations that must be kept in mind during the project. While each kind of flashing requires a slightly different installation process, all require the same basic steps:

  1. Cut the flashing pieces to size, or purchase the sizes of pieces you need.
  2. Lay the flashing in place.
  3. Nail or screw the flashing down.
  4. Apply sealant (usually roofing cement) until the pieces are securely attached to the roof.

While you can purchase premade roof flashing, many roofing professionals choose to create their own custom pieces for each roofing project they work on. They bring a giant roll of sheet metal with them to the project site and cut pieces of flashing as they go, sizing and bending them into just the right shapes for your roof.

Flashing is generally made from aluminum, copper, stainless steel, and galvanized steel. Each of these materials has its own costs and benefits. For example, the higher durability of copper roof flashing comes with higher costs, while aluminum flashing is budget friendly but less hardy than its steel counterparts.

For the average-sized single-family home, expect a full flashing replacement to cost anywhere from several hundred to just over a thousand dollars. A simple repair job is still likely to run you at least a couple hundred dollars.

Lifespan and Signs of Damage

Your roof flashing should last about as long as your roof itself, depending on the metal you use for your flashing. Several kinds of flashing are installed underneath other roofing materials, so it would make your life difficult if the flashing had a shorter lifespan than the roof itself!

The signs of damaged roof flashing are very similar to those of damage on other kinds of roofing materials: dents, tears, corrosion, and loose pieces are all common signs that you should get your roof flashing looked at by a professional.

If you’re experiencing roof leaks or other interior water damage, you should look to your flashing material as the first potential culprit. Because the flashing covers all the edges of your roof, it’s most likely that a leak has sprung up along one of these edges and can be fixed by getting new flashing.

Even if you aren’t having any issues with your roof, the flashing should be inspected annually along with the rest of your roof system.

Keep Your Roof Flashing in Mint Condition

close up to roof flashing of asphalt shingle roof

As you can see, your roof flashing is vital to the health of your home. Choosing your materials wisely and keeping them in good repair can go a long way toward preserving the health of your roof and home.

If you’re looking for a professional roofing contractor to install roof flashing on your home, Level Edge Construction & Roofing is just the company for the job! Our two decades of work in the industry mean that we’ve seen nearly every kind of roof installation out there, and we’re well-equipped to provide you with proper installation of your flashing at an affordable price.

Connect with us today to learn why we’re the best local roofing contractor for all your repair and replacement needs!