Roof Flashing: Types, Materials, and Why It Matters

What is roof flashing?

Roof flashing is thin metal installed at the seams and joints of a roof, like around chimneys, walls, valleys, and vents, to steer water away from those weak spots. Flashing is a key part of keeping a roof watertight, and failed flashing is a common cause of leaks.

Key takeaways

• Flashing is thin metal that seals the joints and edges where roofs commonly leak.
• Common spots include chimneys, walls, valleys, vents, and roof edges.
• Aluminum, copper, and steel are the usual flashing metals.
• Each of the six common types of flashing are designed to handle a different part of the roof in its own way.
• Failing flashing, from rust or lifting, is a frequent source of leaks.

From the ground, a roof can look like nothing but shingles, but a roof is more complex than that. Several components work together to keep water out, and flashing handles the spots where water tends to sneak in, like seams, joints, and edges. Without solid flashing, a home is open to leaks, water damage, mold, and even early roof failure. On Tops Roofing works on more than 900 roofs a year and has served the Raleigh area since 1991, so we have seen how much good flashing matters.

• What roof flashing is
• What flashing is made of
• Types of roof flashing
• Why flashing matters
• Signs your flashing is failing
• FAQ

What Roof Flashing Is

Roof flashing is a thin metal material installed under or alongside the shingles to keep water out of the openings and joints on a roof. Flashing redirects water away from the spots where leaks usually start. Roofers install flashing anywhere the roof surface breaks or meets something else, including the areas below.

• Around chimneys
• Along sidewalls and front walls, where the roof meets a wall
• In valleys, where two slopes join
• At roof protrusions like bathroom vents, kitchen vents, and skylights
• Along roof edges, including eaves and rakes

All of these spots are vulnerable to water, so without flashing, any of these areas can turn into a leak.

What Flashing Is Made Of

Flashing is usually made from aluminum, copper, or steel, and each metal has its strengths.

• Aluminum is lightweight and easy to install, which makes it a very common flashing metal.
• Copper is malleable, bonds well with other roofing materials, and lasts a long time. Homeowners who want an upgraded look often choose copper.
• Steel is galvanized to resist corrosion and bends easily, giving a clean look at a budget-friendly price.

Types of Roof Flashing

All flashing keeps water out, but different shapes protect different parts of the roof, and six types come up regularly.

• Step flashing uses L-shaped pieces set between shingles where the roof meets a wall, running up the rake. Since step flashing stays visible, some homeowners pick copper to match their home's look.
• Counter flashing sits above step flashing on brick or concrete walls, making sure water stays on top of the base flashing and flows down toward the gutter.
• Apron flashing is L-shaped and wraps the base of walls or penetrations.
• Valley flashing runs where two slopes meet in a valley, carrying water off the roof and into the gutters.
• Kickout flashing goes where a gutter ends against a sidewall, diverting water into the gutter instead of down the wall.
• Drip edge attaches at the roof's edge over the fascia and under the shingles, with a bent shape that guides water into the gutters or off the fascia rather than back into the roof.

Why Flashing Matters

A roof leak is a common headache for homeowners, and a leak does more than harm the roof, since water can spread into the attic, walls, ceilings, and living space. Because flashing is built to stop leaks where they usually start, good flashing protects your whole home in a few ways.

• Flashing extends your roof's life, since when a roof leaks, moisture gets trapped in the sheathing, underlayment, trusses, and rafters, and those wet components rot and can lead to early roof failure.
• Flashing helps prevent mold, because water that reaches the attic creates the damp conditions mold loves, which can spread and hurt the air quality throughout your home.
• Flashing protects your insulation, since a leak can soak attic insulation, reducing how well it works and putting more strain on your roof and your energy bills.

Signs Your Flashing Is Failing

Flashing takes a beating over the years, and worn flashing is a common cause of roof leaks, so a few warning signs are good to know.

• Rust, corrosion, or discoloration on any visible metal flashing.
• Flashing that has lifted, loosened, or pulled away from a wall or chimney.
• Cracked or missing sealant where flashing meets another surface.
• Water stains on ceilings or walls near a chimney, skylight, or wall line.
• Daylight or damp spots in the attic around penetrations.

Catching flashing problems early keeps a small fix from becoming a major repair, so when something looks off, have a roofer take a closer look.

Do Not Overlook Your Flashing

Flashing rarely gets much attention, but it plays a real role in keeping water out. Installed and maintained well, flashing adds years to your roof and protects everything below. On Tops Roofing has installed and repaired flashing on Raleigh-area roofs since 1991, and you can request a free estimate whenever you are ready.

FAQ

What is roof flashing?

Flashing is thin metal installed at the joints, seams, and edges of a roof to divert water away from spots that leak easily, like chimneys, walls, valleys, and vents. Flashing is a key defense against roof leaks.

Where is flashing installed on a roof?

Anywhere the roof surface meets something else or has an opening, including around chimneys, along walls, in valleys, at vents and skylights, and along the eaves and rakes at the roof's edge.

What is roof flashing made of?

Usually aluminum, copper, or steel, each with its own strengths. Aluminum is light and common, copper is durable and adds an upscale look, and galvanized steel resists corrosion at a friendly price.

How do I know if my flashing is failing?

Look for rust or discoloration, flashing that has lifted or pulled away, cracked sealant, ceiling stains near chimneys or walls, or daylight in the attic around penetrations. Any of these can point to flashing that needs attention.

Can flashing be repaired, or does it need replacing?

Minor issues, like cracked sealant, can often be resealed, while corroded, bent, or lifted flashing usually needs replacing. During a roof replacement, flashing is typically replaced to keep the whole system watertight.