What is Roof Flashing and Why Is It Important? (2023 Guide)
After reading this guide, you’ll feel much more confident talking with a roofing contractor because you’ll know exactly what roof flashing is and why it matters.
Each product and or company featured here has been independently selected by the writer. You can learn more about our review methodology here. If you make a purchase using the links included, we may earn commission.
If you’re in the market for a new roof or roof replacement, you’ve probably heard a bunch of strange roofing terms like “flashing.” Sometimes it can feel like roofing contractors seem to be speaking a different language.
If you’re a little confused, you’ve come to the right place. After reading through this guide, you’ll have so much knowledge about roof flashing you’ll essentially be a roofing professional yourself.
…But don’t try to install your own roof unless you’re licensed for that.
What is Roof Flashing?
The answer you’ve been waiting for: what is roof flashing? Simply put, roof flashing is pieces of thin metal material that roofers install on certain areas of your roof to prevent water from pooling or seeping into any cracks or joints.
Roofers will typically put a piece of flashing material in and around your roof valleys, eaves and dormers, as well as around chimneys, windows, HVAC systems or any other protrusions from your roof surface. Basically, flashing needs to go in any area where your roof changes angles.
Roof flashing is made from sheet metal and the most common type is galvanized steel, but homeowners will have the option to choose aluminum, lead or copper flashing as well.
If you have a metal roofing system, you may be able to choose flashing made out of the same material.
Why is Roof Flashing important?
Roof flashing is not a fancy add-on that your roofing contractor is trying to upsell you on. It’s an extremely important roofing material that belongs on all roofs — both flat and sloped — and works in tandem with underlayment to protect your home from water damage.
The metal flashing is used to direct water away from areas where it would otherwise pool or enter into joints or cracks. The flashing keeps water running smoothly into your gutters.
Without flashing, your roof would be highly susceptible to leaks, rotting, and mold growth.
Our Favorite Roofing Contractors
Rather skip the reading and start talking to a trusted roofing contractor who’s good at explaining the ins and outs of your roofing project? Reach out to one of our favorite roofing companies by clicking on the links below.
Erie Metal Roofs
Common Types of Roof Flashing
There are many different types of roof flashing. Unless you’re installing your own roof, you won’t need to know all the ins and outs of each one, but here’s a quick overview:
- Base flashing: Used to line the front walls (also called headwalls). Made of one piece of flashing bent down the middle or two pieces of flashing. Installed under the roofing shingles and siding, but over the underlayment.
- Step flashing: Similar to the base flashing, it’s used where the roof deck meets a vertical wall (also called a sidewall) to prevent roof leaks and mold growth.
- Valley flashing: On a roof, valleys are the places where two roof decks slope towards each other (much like a valley between two mountains). This flashing is installed in an “open valley” style so that water can run off the roof and down into the gutters instead of getting pooled in the valley.
- Chimney flashing: No surprise here, this is the type of flashing that wraps around your chimney. Any type of flashing that’s installed against brick or masonry walls is also called counter flashing.
- Skylight flashing: If you have any skylights, you’ll need skylight flashing to protect against leaks, moisture and mold from getting into your home or onto your shingles.
- Continuous flashing: Also known as apron flashing, it’s one long, continuous piece of metal installed where the gutter and roof meet. Many roofing experts advise against installing continuous flashing unless it has built-in expansion joints so it can shift as the house does.
- Drip edge flashing: Drip edge flashings go along the edge of the roof. This is a thin metal flashing that allows the water to drip off the roof without causing damage to your roofing materials.
- Kickout flashing: Also called diverter flashing because it diverts rainwater and moisture away from the cladding of your home and directs it instead into your gutters.
How to Tell If Your Roof Flashing Needs Repairs or Replacements
Roof flashing has a lifespan of roughly 40 years if installed properly. That means it’ll last longer than most roofing materials, including highly popular asphalt shingles.
That said, your roof flashing may need to be repaired before those 40 years are up. Flashing can become loose, corroded or rusted or develop holes from weather exposure.
The job of flashing is to prevent water damage, so it is typically made from water-resistant material such as metal. But if there’s heavy snow or ice buildup, the water can seep under the metal strips as it begins to melt and expand as it refreezes, warping the metal. Weather can also cause the flashing to corrode, leaving small holes that need to be repaired.
Wear and Tear From Weather
One of the most common flashing repairs is locking it back down after it becomes dislodged, which can happen from water damage or from high winds.
Flashing is a crucial part of your roof, so it’s important to have a professional roofer you trust install your flashing. If your flashing is crooked, has gaps or loose pieces, it was probably a poor installation job.
Remember that flashing is one of your first lines of defense against roof leaks, so it’s crucial that it’s in good condition. Make a point to have your flashing checked once a year, but give it the once-over any time you find yourself looking at your roof.
You can repair small holes in the flashing and lock down flashing that has become loose. However, you’ll need to replace your flashing if it’s extremely rusted or corroded or causing leaks.
If you can, you should try to time roof replacements with roof flashing repairs or replacements. Repairing roof flashing can be four to five times more expensive when the entire roof isn’t replaced because of the extra labor involved in removing a section of the roof, repairing the flashing and then re-roofing.
How Can You Maintain Your Roof Flashing?
You’ll want to maintain your roof flashing frequently — at least once a year — to help prevent major damage or costly repairs in the future.
You should clean your roof flashing annually, wiping away any debris, mold or corrosion. You can clean flashing with soapy water mixed with a touch of lemon juice or vinegar with a piece of super-fine steel wool.
Even if you don’t see any issues, it’s a good idea to redo the caulking around your flashing every two years or so. If you live in a place with severe weather it might need more frequent care.
How to Hire a Roofer to Help With Roof Flashing
Having a secure roof above your head is one of the most important things for a homeowner. So you want to find a reliable roofing company to install your roof flashing.
As we mentioned before, it’s best to install new roof flashing alongside your roof replacement to get the most financial benefit.
If your roof repair needs go beyond just flashing, ask your roofing contractor if you can bundle your repairs and get a discount.
You can read our guide for how to find the best roofing contractor here or click one of the links below to get connected with one of the roofing companies that EcoWatch has vetted as trustworthy.