Roofing materials like shingles leave gaps and creases in areas that are otherwise hard to address with shingles alone. So the best professional roofers utilize pieces of metal flashing (manufactured or hand-bent in various ways) to cover and protect what the roofing material can’t. In this article, I’ll talk about metal flashing — its types and materials — and help you have a better, more confident understanding of this critical roofing component.
If you’re concerned that your roof’s flashing is damaged or incorrectly installed, you can contact my recommended roofers:
What Is Roof Flashing and Why Do I Need It?
Roof flashing directs water away from areas it might seep into, like crevices and seams between sheathing. The most vulnerable areas are where the roof’s surface ends or is intersected by a different surface that makes up the structure of another architectural element or housing utility, like:
- Dormers
- Chimneys
- Vertical walls
- Parapets
- Cupolas
- Vents
- Skylights
- Roof edges
- Roof valleys
Flashing is a foundational component in all roofing systems. Quality installation and maintenance are critical for the long-term health of a house. In fact, installation by a reputable professional is an investment that can save you in the long run. Check out our comprehensive guide on tips for finding reputable roofing contractors.
Because metal flashing comes in a few different materials, it can also be a nice decorative element to add contrast or visual interest to your roof. Traditionally used materials like bare copper or lead-covered copper add a bit of “days gone by” charm to houses, new or old.
Flashing is a critical component of a roofing system. While it doesn’t need regular maintenance, keeping an eye out for any damage or rust is a good idea.
What Are The Different Types of Roof Flashing?
Roof flashing comes in various types to suit a variety of needs. Step flashing and continuous flashing are most frequently used around “protrusions” into the roof, like chimneys and dormers. Drip edge and valley flashing are protective elements of the roof itself, and counter flashing is used in a variety of specialty circumstances — for example, to complement step flashing around a chimney or skylights.
You can also check out this video by Bill Ragan Roofing Company for more information and a rundown of how the different types of flashing are used.
In the sections below, I’ll discuss each type in more detail.
Step Flashing
Step flashing is an angled form of flashing that sits between individual shingle courses, against the wall, and beneath the siding of a perpendicular surface (like the wall of a dormer). In that way, it “steps down” with each course of shingles along the pitch of the roof to ensure that water doesn’t leak down into the seam where the roof sheathing meets the wall sheathing. In the case of brick walls or chimneys, this flashing is often purposefully exposed to create an interesting visual element. It needs no maintenance beyond basic inspection, and a roofing contractor will replace it when working on your roof.
Read also: 3-tab vs architectural shingles
Continuous Flashing
Continuous flashing (sometimes called apron flashing) is similar to step flashing. Continuing with the example of a dormer, the dormer wall facing toward the edge of the roof would be flashed with one long piece of flashing (hence, continuous, as opposed to step.) Like step flashing, it’s bent into an angle so that one side tucks under the siding, but instead of going in between shingles, it goes over them. For maintenance, clean it as needed. A roofing contractor will replace it when they put on a new roof.
Read also: The Process of Roof Moss Removal
Drip Edge Flashing
Drip edge serves as a “cap” on the exposed edges of the wooden sheets that comprise the roof deck. Where there are gutters, there is drip edge — and even in some places there aren’t gutters, there is drip edge. Even though shingles and other roofing material overhang the edge of the roof, water can still end up riding up the underside of the shingle and into the edge of the wood sheathing. This kind of water exposure to the edges of common roof deck material, like oriented strand board, commonly called OSB, can rapidly degrade the material’s structural integrity. The drip edge prevents that from happening. Drip edge is replaced with every new roof installation, and maintenance outside of light cleaning as needed is rarely necessary.
Valley Flashing
Where differing roof pitches come together is called a valley. Like valleys in nature, it’s where water is drawn to and collects to be drained away by gravity. Roof valleys are a natural course for water to collect and flow, and roofers take extra precautions to ensure they’re thoroughly protected against water damage. Valley flashing is an exposed flashing that runs the length of an open valley (as opposed to a closed valley where shingles are run clear through it.) Some people like the look of this exposed valley flashing, and it’s also beneficial to allow the robust metal to bear the brunt of flowing rainwater.
Counter Flashing
Counter flashing, as the name suggests, runs counter to most other types of flashing. It’s the flashing that is usually observed around a brick chimney as part of the system of chimney flashing. Though it can look like step flashing when used like this, it’s actually bent opposite of step flashing. If you look closely, you can see that one side is embedded in the mortar between brick courses, while the other “ear” is bent down toward the roof. Counter flashing works in concert with step flashing around the chimney (and in other areas) to completely protect vulnerable areas.
What Types of Materials Are Used for Roof Flashing?
Roof flashing is manufactured from malleable metals like copper or aluminum. Below, I’ll shed light on some of the most used materials and their advantages (or disadvantages).
Aluminum
Aluminum is a very common flashing material and is suitable in all cases. It’s cheap, readily available, and easy to work with. It comes in many colors to match any roofing material or siding color. The drawback is that it doesn’t necessarily add anything to the roof’s beauty. At best, it blends in unnoticed.
Copper
Copper is a traditional flashing material that has been in use for centuries. It’s malleable and pretty, and many people consider the patina it gains over time charming. The downside is that copper can be expensive, especially pure copper. There are other options available, though. Lower-purity copper alloys have the look and appearance of copper but at a cheaper cost.
Lead-Coated Copper
Like copper, lead-coated copper is a time-honored flashing. Don’t be scared by the name. Despite being coated with lead, the Environmental Protection Agency (EPA) makes no mention of any environmental hazards associated with it. Lead-coated copper has a lustrous gray look that, like copper, gives a house a bit of historical flair.
Galvanized Steel
Galvanized steel is a cheap and functional flashing material. It will (and has) performed well over the decades, but it’s susceptible to discoloration by various means. Of all flashing material, it’s the least appealing option to most. It lacks somewhat in the looks department, and few people find it aesthetically desirable. While galvanized steel is cheap, aluminum is only slightly more expensive and has better long-term qualities.
How To Choose the Right Type of Material of Roof Flashing for Your Home
The right material for your roof comes down to style and budget. While all flashing material protects a house equally well, not all have the character that a homeowner is looking for, nor do they all have the same price tag. Though steel and aluminum are approximate in value, copper and lead-coated copper can be costly, especially for a large or complex roof.
| Type of Flashing | Cost per Square Foot | Average Life Span |
| Aluminum | $1.75 | 40–50 years |
| Copper | $14 | 60–100 years |
| Lead-coated copper | $12 | 75–100 years |
| Galvanized steel | $0.90 | 60–80 years |
DIY Vs. Professional Flashing Installation
Installing roof flashing is best left to professionals. Aside from a few manufactured pieces, much of a roof’s flashing must be handmade with brakes and shears to fit the specific application. Flashing gets replaced with each new roof, so homeowners rarely need to be concerned with it.
If you want a specific flashing material, mention it to your roofing contractor. In many cases, contractors will use a standard flashing material, usually an economical material like aluminum or galvanized steel. Owing to the expense of copper or lead-coated copper, contractors won’t assume that’s what you want. So, if you want copper or something like it, be sure to specify that.
How To Maintain and Repair Roof Flashing Over Time
Because flashing is metal and generally replaced with each new roof, no maintenance is necessary. If it’s undamaged by wind or weather, it will last until the next roof goes on. If it gets dirty, a light cleaning with any general cleaner should be sufficient to restore it to its original look. If you experience a bad storm, I would check afterward to make sure it’s undamaged.
Flashing needs little maintenance in between new roofs. Light cleaning and basic inspection for damage are all you need.
But what about damage — are there any signs you should look for? Regrettably, it can be difficult to know. Roof leaks can be hard to track down. I suggest not worrying specifically about what damage failing flashing might cause and instead keeping an eye out for any damage. If you find damage, a roofing professional will be better positioned to inspect your roof and find what specifically has failed. Generally, look out for cupping shingles, swollen or sagging areas, rust stains around flashing, water stains in vulnerable or odd areas, interior leaks, mold, and staining.
So, What Is The Best Roof Flashing For You?
In the end, you can’t go wrong. Whatever roof flashing you or your contractor choose will be sufficient for your long-term needs. Though copper may be a little outside the budget of some, aluminum or galvanized steel are still fine choices that will keep you and your house happy and dry for years to come.
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Frequently Asked Questions
What happens if you don't have roof flashing?
In short, you’ll have roof damage (and likely in your house’s interior.) Flashing is a critical part of all roofing systems. A homeowner or prospective homebuyer should ensure that flashing is installed correctly.
What else is there on a roof besides flashing?
A roof has many parts, from its roofing material (like shingles or shakes) to ridge vents, chimneys, utility vents, gutters, and fascia. There are also plenty of unseen things like starter strips, ice and water barriers, and underlayment.
Is flashing a waterproofing material?
Yes, flashing is a principal component of a roof that helps to shed water and prevent it from entering the house.
