What Is Roof Flashing? (Cost, Benefits & More!)
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What Is Roof Flashing? (Cost, Benefits, & More!)

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Posted By: Roof Troopers

close-up of metal roof with flashing installed for water-proofing

Roof flashing is an essential material that all roofs need. Of course, most homeowners don’t really know what roof flashing is, what it does, or why it’s so important. 

However, one thing that all homeowners do know is how stressful water damage can be to their roofs and how expensive it can be to repair or replace a water-damaged roof. That’s where roof flashing comes in.

In this article, we’ll give you the rundown on roof flashing — including the cost of repairs and signs of damage. Keep reading to learn more.

What Is Roof Flashing?

metal roof with base flashing on chimney to prevent leaks

Put simply, roof flashing — also referred to as metal flashing — is a thin, galvanized metal that’s applied around your roof’s drip edge, sky lights, valleys, vents, and chimneys. Its purpose is to redirect the flow of water to prevent it from seeping into any of the cracks and openings throughout your roof. 

The most common material used for roof flashing is aluminum as it’s the most budget-friendly and durable metal. However, you’ll also find that roof flashing is also made from steel, copper, and other metals.

Roof flashing is critical to your home’s protection. Without this material, your roof’s chances of excess moisture build up and leakage are extremely high. 

The Most Common Types of Roof Flashing

Roof flashing is categorized by the area to which it is applied. Therefore it can be broken down into these common types:

  • Base flashing: Base flashing is typically used for roofs with chimneys. These types of roofs require multiple pieces of metal flashing for optimal waterproofing.
  • Step flashing: Step flashing is installed in multiple layers to prevent the roof’s walls from absorbing water. This type of metal flashing is rectangular in shape and bent at a 90-degree angle from the middle to create a water-repelling slope.
  • Valley flashing: Valley flashing gets installed around open roof valleys to aid them in channeling rainwater off the roof and to help prevent the buildup of debris that occur during storms.
  • Drip edge flashing:
close-up view of metal drip edge flashing on roof
  • Drip edge flashing is installed on the edges of a home’s roof. They work by guiding rainwater off the roof’s drip edges, thereby preventing excess moisture from entering the shingles and causing the wood on your roof edges to rot.
  • Vent pipe flashing: Vent pipe flashing is installed over a roof’s round vent pipes. They work to seal the ventilation pipes, keep out drafts, and prevent leaks.
  • Continuous flashing: Continuous flashing involves the installation of a long metal sheet on the surface of a home’s roof. Continuous flashing directs water flow right to the roof’s edge and into the gutter.
  • Counter flashing: Counter flashing is installed on top or opposite of the base flashing. This type of flashing works to prevent water from entering the roof’s shingles and chimney.

Roof Flashing Benefits

There are three main benefits that are associated with roof flashing. Here are some of the benefits of installing roof flashing:

1) It Prevents Water Damage 

red metal roof with flashing preventing water damage during rain

A home’s roof has a lot of unseen nooks and crannies that are sometimes even unseen by professional roof inspectors. 

By installing roof flashings, you can seal all the unseen cracks to serve as a waterproof layer that protects your roof’s surface by preventing moisture from seeping in. Without roof flashing, rainwater and melted snow would simply run down your roof and end up seeping into your home — causing extensive damage.

2) It Further Protects Your Roof

Metal flashing doesn’t just protect your roof and home from water damage but all of the other elements, too. You can think of roof flashing as a type of shield that protects your walls, shingles, and chimney from all types of damage that can occur to your roof, including flying debris.

By protecting your roof, flashing also increases its longevity.

3) It Helps You Save on Maintenance Costs

By protecting your roof’s surface from potential water damage and elemental hazard, your roof flashing is also saving you from having to replace your roof early or repair it frequently. Roof flashings are also very easy and affordable to maintain, as they can be reused as long as they’re still in good condition.

Signs It’s Time for New Flashing

close-up of roof chimney with rusted flashing in need of replacement

If you already have roof flashing but are noticing the following issues, then it’s likely time to call your local roofing contractor for repairs:

  • Rust stains on the firebox of your chimney
  • Water stains on your ceilings and walls
  • Water leakage in the form of drips and puddles
  • Corrosion (rust) or holes on the actual flashing sheets

How Much Does it Cost to Replace Flashing on a Roof?

Upon inspection conducted by a professional, you may find that you only have a minor problem on your hands or will need to completely replace entire strips. Generally speaking, the cost of repairing flashing ranges from $15 to $25 per linear foot. This typically includes the cost of the new flashing as well as the caulking needed to seal it in place — which usually costs around $10 or more on its own.

When you calculate the cost per linear foot, most flashing repair costs range between $200 and $500 on average, while total replacement costs range between $300 and $1,500. For larger chimneys and stone chimneys, you can expect to pay upwards of $2,000 for flashing replacement.

The other factors that make up the total cost of a flash replacement or repair — aside from labor — include:

  • The flashing material used
  • The size of the area that needs new flashing and the extent of the damage
  • Chimney size and type (if applicable)
  • Roof configuration
  • Inspection
  • Cleanup

Is It Time to Replace Your Flashing?


If you notice any of the above signs of flashing damage, you’ll want to address them immediately. Otherwise, the damage can quickly spread throughout your home’s interior and the rest of your roof — resulting in the need for a new roof and other more costly repairs.

Let Roof Troopers inspect your flashing and the rest of your roof before it’s too late. Get in touch with us today to schedule an assessment and to learn more about our roofing services.


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