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If you have your roof inspected, you’ll probably hear a lot of terms you aren’t familiar with. “Roof flashing” may be one of them. While you may understand shingles, gutters, and weather shields pretty well, roof flashing rarely gets enough attention in roof repair and replacement scenarios.

However, flashing is one of the most important parts of your roof. Without proper flashing, your roof would leak all the time and cause major damage to the rest of your home.

The fact is that many unprofessional roofing contractors simply don’t install flashing correctly. This can lead to immense problems down the road if you don’t know how flashing works or how it should be installed and maintained.

Luckily, roof flashing is fairly simple to understand. But in order to make sure your current roof flashings are properly installed and in good condition, you’ll need to dive into the techniques used by professional roofers. Let’s look at the most important aspects of roof flashing, so that you can be informed for your next roof repair or replacement project.

What is roof flashing?

The purpose of roof flashing is to protect your roof joints from leaking water. It directs water away from joints back onto the shingles, into gutters, or away from the house entirely.

Flashing often appears as a piece of metal trim (sealed with caulk or rubber) that covers the seams surrounding various penetrations in your roof. Penetrations include things like chimneys, skylights, roof vents, dormers, and walls. You may also see flashing in valleys (the inward crease in a roof where two roof slopes meet) and at the rake edges of your roof.

There are three materials most commonly used for flashing:

  • Aluminum – While aluminum is the least expensive flashing material, it still holds up decently over time. Many homeowners opt for aluminum flashing for this reason. However, it may be more susceptible to deterioration, and impact damage than other materials.
  • Steel – Steel is a thicker and stronger material than aluminum, but is still relatively affordable. Most roof flashing uses 26 to 28 gauge steel, especially for longer stretches of apron flashing.
  • Copper – Copper flashing is the most expensive type of material, but it can also last up to 100 years. It can also provide curb appeal, depending on the style of your roof.

Types of roof flashing

Different areas of your roof call for different types of flashing. In order to understand your roof inspection and make sure your roof is protected, you’ll want to be familiar with these different types, what they look like, and how they are installed.

Base flashing

Base flashing (also called “apron” flashing or continuous flashing) is usually installed at the base of the headwalls (walls that face the same direction as the downward slope of your roof).

Base flashing is often installed as a single strip of metal along the bottom of the wall, where it meets the shingles. Because base flashing is installed underneath the siding and shingles, it is rarely visible from the ground.

While some inexperienced contractors use continuous flashing on sidewalls (walls that are perpendicular to the roof slope), this isn’t the best practice. Because of the way sidewalls make contact with your roof slope, continuous flashing is less likely to stop water from leaking into the home if it becomes damaged. If one part of it breaks, the entire strip is susceptible to leaks — water will run downhill underneath the metal (and into your plywood decking).

Step flashing

Step flashing is a reliable, time-tested flashing method used for many different parts of a roof. It’s usually considered the best type of flashing to use for sidewalls.

The technique involves layering multiple small L-shaped pieces of metal between shingles, cascading up the side of a wall. This way, there is always another piece of material under each shingle or piece of flashing. This creates a better protective seal so that if one piece fails, there are more layers to catch the water and direct it back on the path toward the gutter.

Well-installed step flashing is usually difficult to see. Like base flashing, step flashing is installed underneath the shingles and the siding. Most of the time, only a small portion of it is visible from the ground.

Counter flashing

Counter flashing is most often installed at the base of a chimney and is usually visible from the ground. While it may appear to be installed in a “step-like” fashion, counter flashing is almost always installed on the outside of walls and shingles. Instead of being secured with surrounding materials and nails, roofers install counter flashing by cutting directly into the mortar joint of a chimney or wall with a concrete saw. The connection between counter flashing and the roof system is usually much stronger than any other type of flashing.

Valley flashing

When two downward slopes of a roof meet to form a crevice, this is called a roof valley. Since two adjacent roof slopes rarely meet perfectly, there is often a crevice between them that can leak if not properly sealed.

On some occasions, your roofer may be able to weave the two layers of shingles together to create a seal over the joint. However, this only works with thinner and more pliable asphalt shingles. If you’re using anything thicker than 3-tab asphalt shingles, your roofer will need to install valley flashing to protect your home from leaks.

Like many other types of flashing, valley flashing is installed with the edges tucked underneath the shingles. When installed correctly, valley flashing should direct water straight into your gutters.

Kickout flashing

Kickout flashing hangs slightly off the edge of your roof, in order to direct water into the gutters and prevent it from hitting a nearby wall. It’s typically installed directly at the end of the step flashing and is shaped like a rectangular cup or bucket. Without it, water that runs down the step flashing could miss the gutter and instead drain into your siding. Kickout flashing redirects the water by catching it before it hits the wall and allowing it to flow over into the gutter.

Drip edge flashing

The purpose of drip edge flashing is to protect water from damaging your fascia or soffit. This type of flashing is most important at the rake edges of your roof (the edges of a gable roof that form an “A” shape — where the fascia is most visible and there are no gutters). However, it can also be helpful on areas of your roof where water runoff is a major problem thanks to clogged gutters or ice dams. Most of the time, drip edge flashing will allow water to drip straight off your roof. Other times, it may run off into the gutters.

Vent stack flashing

Because vent stacks are often circular penetrations, they usually require a special kind of flashing. Most of the time you will need both a metal component and a rubber gasket to create a good seal. When a roofer installs flashing around a vent stack, the metal piece should be twice the size of the rubber flange, and shingles should be cut to fit around the area to form a proper seal.

Roof flashing maintenance tips

Now that you know the different types of flashing, it’s important to know the best practices for installation and maintenance so your roof is continuously protected. If done right, your flashing should last the full lifespan of your roof (and maybe even longer).

Here are a few tips to help you maintain proper flashing:

Inspect your flashing often

If possible, have your roof flashing inspected at least once a year. During the inspection, your roofer may be able to spot small instances of damage that you can repair before they become bigger problems.

Signs of flashing damage include:

  • Rust
  • Cracks or splits
  • Buckled metal
  • Holes
  • Curling shingles near the flashing
  • Leaks inside your home

Don’t reuse damaged flashing

Unless your flashing is in near-perfect condition, don’t reuse it when you replace your roof. Even the smallest crack can allow water to leak underneath the shingles. This can ruin your plywood decking before your new roof reaches the end of its lifespan. Most of the time, it’s best to replace all your flashing during a roof replacement project. However, if the flashing is not buckled, rusted or deteriorated and there are no cracks, tears, or holes, you may be able to reuse it if you are trying to save money on a roofing job.

Replace flashing when upgrading roofing materials

When you are upgrading to thicker roofing materials such as synthetic roofing, it’s always best to replace the flashing as well. Your previous flashing was likely bent and cut to fit perfectly with the thinner roofing material. With thicker materials, the previous flashing may not have the right fit and your roofer will probably need to cut and bend it again. But if you’re working with flashing that has already been bent (and exposed to the elements) bending it again may weaken the material. Your roofer should use new metal to create a strong seal with your new roof.

Install flashing correctly

The most important part of ensuring longevity with your roof flashing is to have it installed correctly in the first place. High-quality flashing work requires special skills and additional effort to install correctly. But many roofing contractors out there only know how to install shingles fast. While these new roofs may feel protective, they will likely start leaking very quickly due to improper flashing work.

The best way to guarantee proper protection from leaks is to hire a trusted roofing company with a reputation for high-quality work. While some cheap contractors may try to win your business by offering the lowest price, this is often a sign that they are cutting corners. Instead, you’re better off choosing a roofer that charges enough to do the job right the first time.

Final thoughts

Roof flashing is often overlooked by roofers and homeowners alike. But it isn’t something anyone should ignore. It’s an incredibly important part of your roofing system that ensures proper water runoff and prevents leaks. If not installed correctly, it can allow water to leak through your shingles, into your plywood decking and beyond. This can cause problems for virtually every part of your home.

As a homeowner, it’s important to understand the different parts of your roof system. You want to make informed decisions about how to maintain your roof, and which roofing company to hire for your next repair or replacement project.

The key to proper roof installation is attention to detail. But many roofers simply don’t take the time to study the roofing trade or learn what techniques work best. By hiring a roofer that truly knows the craft, you’ll be able to pay for a roof that adds value and protects your home for many years to come.

At Baltic Roofing, we’ve taken the time to learn proper roofing techniques. Our main priorities are correct installation and high-quality workmanship. At the end of the day, we can take pride in our work because we pay attention to the details that keep your home safe from the elements.

If you’re unsure about the condition of your flashing, or you just want to be sure it’s installed correctly, contact us for a roof inspection today. We’ll provide you with the most effective options to make sure your roof is in great shape.

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