A Complete Guide to Metal Roof Flashings
- On October 6, 2022
When it comes to your roof system, flashing is one of the most critical elements. Flashing helps keep water out of your home and protects vulnerable areas, such as around skylights, vents, and chimneys. Because of how important it is, there are certain things you’ll want to know about flashing, whether your existing flashing requires repair or you’re replacing your entire roof.
What is Roof Flashing?
Flashing is a thin, waterproof material used to seal the joints between different parts of the roof. The purpose of flashing is to prevent water from seeping through these joints and causing damage to the home. When properly installed, roof flashing helps to direct water away from these areas and prevents it from leaking into your home. Flashing is typically made of metal, although it can also be made of other materials, such as plastic or rubber.
Different Types of Metal Roof Flashing
There are several types of metal roof flashing, each of which is best suited for a specific purpose. The following are the different types of flashing that are commonly used for a standard roof system:
Base flashing is the bottom piece of a two-part flashing system that helps ensure that rainwater hits a flashing surface and is guided downwards off the roof. It’s often used around roof features, such as chimneys.
Step flashing is used where the roof intersects with a vertical wall, such as around dormers. It is installed in a series of overlapping sections that “step” up the wall. Without step flashing, water would be able to get in behind the siding and cause damage to the wall.
Counter flashing is the top layer of flashing of a two-part flashing system. It’s positioned opposite to base flashing.
Continuous flashing is a long piece of metal meant to guide water down to the shingles below. It’s often referred to as apron flashing. The drawback of continuous flashing is that it requires built-in expansion joints so that it can move as the home expands and contracts over the years.
Valley flashing is used in your roof’s valleys or low areas. It is installed over the top of the shingles and under the valley metal. Valley flashing helps to direct water away from these low areas and prevents it from leaking into your home.
Drip Edge Flashing
Drip edge flashing is a thin piece of flashing used along the edges of your roof. It is installed over the top of the shingles and under the gutter. Drip edge flashing helps to direct water into the gutter and prevents it from spilling over the edge of your roof.
Kickout flashing is a type of flashing that’s used to bridge the gap between where the gutter system begins and the step flashing ends. The use of kickout flashing helps ensure that rainwater falling down the roof makes its way into the gutter.
Roof Flashing Sizes You Should Know
The size of your flashing depends on various factors. For example, step flashing pieces should be 10 inches long and at least 2 inches wider than the exposure of the shingle. If you’re installing flashing around a plumbing vent, it should not only be long enough to surround the entire vent, but it should also be wider than the diameter of the vent.
Different Metal Roof Flashing Materials
Metal tends to be the most suitable material for flashing because it is durable and waterproof. However, there are a few different types of metal that can be used for flashing. The following are the three most commonly used metals for roof flashing:
- Aluminum: Aluminum is a lightweight metal that is easy to form. As such, it is often used for custom flashing applications. However, aluminum flashing used with concrete or masonry will need to be coated. This is because uncoated aluminum will react to alkaline surfaces, leading to degradation. Coating aluminum will also improve its corrosion resistance.
- Copper: Copper is a heavy metal known for its durability and will typically last a very long time. The only real disadvantage of using copper flashing is that it will eventually discolour into a patina. Some homeowners may dislike this aesthetic, especially if it doesn’t complement their home’s existing look. However, other homeowners may like how this looks.
- Steel: Steel combines the best of both worlds. It’s extremely durable, will last a long time, and is easy to work with, making it perfect for custom flashing. It’s also highly resistant to corrosion when galvanized and offers a look that is appealing to most homeowners.
Roof Flashing Techniques
Proper installation is critical to the effectiveness of your roof flashing. If it’s not correctly installed, it won’t be able to do its job properly and will likely fail prematurely. The following are the three main techniques used to properly install roof flashing:
- Step Flashing: Step flashing is the best technique for installing flashing where the roof face meets a wall. It involves installing the flashing under the shingles and over the wall, creating a “step” effect with layers of shingles between the flashing. As a result, when rain hits the roof, the water will simply pour down each step down the roof.
- Counter Flashing: Counter flashing is a technique used to install flashing around chimneys. It involves installing two pieces of flashing. The first is installed around the base of the chimney. The second (which is known as the counter flashing) sits over the base and is embedded into the chimney’s masonry.
- Plumbing Vent Boot Flashing: Plumbing vent boot flashing is a technique used to install flashing around plumbing vents. Vent flashing is a cylindrical boot that fits around the vent. Its height forces rainwater to move around the vent, so it doesn’t seep in.
Roof Flashing Installation
The difficulty of the installation depends on the technique being used. For instance, step flashing is the most challenging technique because it has to be done as you add layers to the roof. It also needs to be installed before the siding since the siding will need to cover the top of your flashing. Step flashing must also extend between 8 and 14 inches above your roof shingles.
How To Install Step Flashing with A Wall Corner
Step flashing becomes a bit trickier if there’s a wall corner on the rooftop. It means that you’ll have to create a corner flashing piece. You’ll need to install the underlayment and the shingles up to where your wall starts so that the corner flashing can also rest on a shingle. Once you install the corner flashing, it must bend tightly around the corner and extend at least eight inches above your shingles. You will then need to cover that corner flashing with a second piece of flashing.
How To Install Step Flashing Without a Wall Corner
If there’s no wall corner to worry about, you won’t need to create any corner flashing pieces. However, you will need to install kickout flashing so that you can guide rainwater down the roof and into the gutter.
What Are the Signs of Metal Roof Flashing Failure?
Your flashing will need to be visually inspected to determine if it needs to be repaired or replaced. However, if you notice leaks in your roof, there’s a chance it will result from failed flashing. With that in mind, the following are a few problems that indicate metal roof flashing failure:
- The flashing is physically damaged, bent, or has holes in it
- The flashing is loose
- The flashing is rusted or corroded
- The flashing is missing or has loose nails
- The flashing’s sealant has dried up
How To Repair Metal Roof Flashing
Repairing metal roof flashing isn’t as easy as you might think. The first thing you’ll need to do is to remove any shingles that cover up or surround the flashing. You may also have to remove undamaged flashing to get to the damaged components. The sealant will then need to be scraped off.
Once the underlying roof is exposed, you should check it for possible damage that needs to be repaired before you replace the flashing. Finally, you’ll need to replace the damaged flashing and re-install the shingles.
Can Metal Roof Flashing Installation Be A DIY Project?
Unless you have previous roofing experience, installing or repairing flashing is a task best left to the professionals. Not only is getting up on your roof a dangerous proposition but installing flashing correctly is crucial to the longevity of your roof. Improperly installed flashing is one of the leading causes of water damage to homes, so the job must be done right. Trying to do it yourself could do more harm than good, which is why it’s better to work with a professional contractor.
Get Comprehensive Metal Roof Installation with Us
Here at Ironclad Roofing, we install high-quality metal roof systems and accessories that will protect your home against the elements and stand the test of time. To request a free estimate or to submit a general inquiry, contact us online or call us at 1-888-530-1347 today.