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old house roof tiles before roof flashing with windows
old house roof tiles before roof flashing with windows

Roof Flashing: What It Is, What It Costs, and When to Replace It

Roof flashing is an essential material that all roofs require to function properly. However, most homeowners have no idea what it is — which means they also have no idea when it needs to be replaced

Homeowners that don’t keep up with their flashing are bound to experience the stress of water damage and its associated costs. That’s why we’re taking the time to cover everything you need to know about flashing, including the signs of damage and the cost of repairs, in this article.

Read on to learn more and prepare yourself.

What Exactly Is Roof Flashing?

Flashing is the thin, galvanized metal that’s applied around a roof’s drip edge as well as its skylights, valleys, vents, and chimneys. The purpose of this roofing component is to help your roof redirect water flow to prevent it from seeping into any cracks and openings around vulnerable areas.

Aluminum is the most commonly used material to create roof flashing, as it’s the most affordable and durable metal on the market. However, you’ll also find that it’s also commonly made from steel, copper, and other galvanized metals. 

You can think of flashing as one of your roof’s most critical components regarding your home’s protection. Without it, your roof would be extremely vulnerable to excess moisture build-up and leakage.

The Various Types of Flashing

new tiles placed after roof flashing

Roof flashing is categorized by the part of the roof it’s applied to. The most common types of flashing include:

  • Base flashing: Base flashing is used on roofs with chimneys. These types of roofs typically need multiple pieces of flashing for optimal waterproofing around the base of external components. 
  • Step flashing: Step flashing is rectangular in shape and bent at a 90-degree angle in the middle to create a water-repelling slope. It’s installed using multiple layers to prevent the roof’s walls from absorbing water by leading that water away from the roof.
  • Valley flashing: Valley flashing is installed around open roof valleys and works by channeling rainwater off the roof. They also help prevent the buildup of debris that may gather during storms or heavy winds.
  • Drip edge flashing: Drip edge flashing is installed on the edges of the roof. They guide rainwater off the roof, which prevents excess moisture from getting into the shingles and causing rot.
  • Vent pipe flashing: Vent pipe flashing is installed around the roof’s vent pipes. This flashing seals the ventilation pipes, which keeps out drafts and prevents leaks from occurring.
  • Continuous flashing: Continuous flashing is a long metal sheet that’s installed on the roof’s surface, just beneath the shingles. Continuous flashing is what directs water flow over to the roof’s edge and straight into the gutter.
  • Counter flashing: Counter flashing is installed either on top or opposite of the base flashing. It works to prevent water from seeping into the roof’s shingles and chimney, if there is one.

What Does Flashing Do?

As you likely know by now, flashing exists to redirect water away from your roof. However, that’s not its only benefit. 

Here’s an overview of what flashing does for your home:

It Prevents Water Damage

Wherever your roof meets another component or corner, there are open spaces that water can get into. The flashing seals all of these spaces plus unseen cracks, which serves as a waterproof later. 

Without flashing, rainwater, melted snow, and excess moisture would simply build up around the various areas of your roof and end up seeping into your home. Eventually, this would cause extensive damage to your home’s structure.

It Protects Your Roof

Flashing isn’t just for waterproofing. It also acts as an entire shield that protects your home from all the other elements. This would include your roof decking, walls, shingles, chimney, and other components — roof flashing protects all of these things from the damage that can occur, including loose and flying debris.

By acting as a protective shield, flashing also increases the lifespan of your roof.

It Helps Save on Maintenance Costs

By protecting your roof from all kinds of damages, your roof flashing is saving you from frequent repairs and replacements — which can become costly. Flashing is also very easy to maintain, as well as affordable, as it can be reused for however long it remains in good condition.

When Is It Time For New Flashing?

roofer working on roof flashing chimney

It can be difficult to tell when you need new flashing for your roof, so you’ll want to keep an eye out for the following signs:

  • Rust stains on your chimney’s firebox
  • Water stains on ceilings and walls
  • Water leakage in your attic, access space, or top-floor ceiling
  • Corrosion/rust or holes on the actual flashing sheets

Rust is usually the number of signs that your roof’s flashing is going bad. If you notice rust or any of the other signs, you’ll want to get in touch with a reliable roofing contractor right away.

How Much Does Roof Flashing Cost?

Generally speaking, the cost of roof flashing will range between $15 and $25 per linear foot. However, the installation process and materials needed, such as roof caulking, will add to the overall cost of replacing your roof flashing. 

After calculating the cost of materials per linear foot, most flashing repair jobs cost between $200 and $500 while a complete replacement can cost upwards of $1,500, depending on the other components of your roof.

Of course, the ultimate cost will depend entirely on what your roofing contractor finds throughout their initial inspection. They may find that you need a simple repair or have a lot more damage to worry about.

The other factors that go into the total cost of a flashing replacement or repair outside of labor include: 

  • The flashing material 
  • The size of the area that needs new flashing
  • The extent of the current damage
  • Chimney size and type 
  • Your roof configuration
  • Inspection (not all roofers offer free inspections)
  • Cleanup
  • Other damages that need repairs before the flashing can be installed

Does Your Roof Need New Flashing?

roofer fixing the flashing damage

It’s important that you address any flashing damage as soon as possible. Otherwise, that damage will worsen and spread throughout your home’s structure and interior — which will result in even more costly repairs.

The professional and skilled professionals at Melo Roofing are here whenever you need a roofing inspection and expert opinion. Give us a call today to have your flashing inspected and to make sure that you have a solid roof over your head.


Can I fix roof flashing myself?

Fixing roof flashing can be a DIY task if you’re comfortable with roofing repairs.

Do you put flashing before shingles?

Yes, flashing is typically installed before shingles to ensure proper waterproofing.

Can water get under roof flashing?

If improperly installed or damaged, water can indeed get under roof flashing, leading to leaks.

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