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How to Install Roof Flashing: Step-by-Step Guide

close up image of roof and chimney with metal roof flashing installed

A new roof installation is a big job and can set your roof up for either a long-lasting life or repeated issues. So you’ll want to ensure that it lasts as long as possible with as few issues as possible. No one wants the headache of water leaking into their home because of an improper installation, missing shingles, or damaged roof flashing.

With the proper building materials, your roof will last for decades, and how to install roof flashing is a key skill any DIYer should know.

So what is roof flashing?

Roof flashing is a thin metal you must install on the roof surface. It is placed in the roof valleys, along the roof’s edge, and along the chimney or vents. The flashing directs water away from the perimeter and any roof features. The flashing will prevent leaks at the seams and joints on your roof.

Read along for our guide through the process.

Why is Roof Flashing Important?

how to install roof flashing on chimney with metal roof photo

You must install the proper flashing to get a watertight seal on your roof. Flashing is one of the most essential roofing materials you can install, as it is a main player in the integrity of your roof. To protect your home from harsh weather, leaks, and structural damages, every homeowner should know how to install roof flashing.

It’s also important to note that roof flashing is often not up for debate. Your area’s building code will require that every rectangular piece of flashing is installed correctly.

Types of Roof Flashing

Below, we’ll cover the various types of roof flashing, their benefits, and the proper installation technique for a long-lasting, sturdy rooftop.

Keep outside elements such as wind and rain out of your home by following this guide.

Step Flashing

close up view of roof step flashing on brick chimney

Step flashing works with counter flashing to direct water to your gutters. The counter flashing is sawed into an existing mortar joint with the metal coming over the top of the brick.

When you install counter flashing, it must overlap so water cannot leak behind.

This is a common flashing type for the edges around the base of chimneys. Typically, it would help if you fabricated a piece of flashing that fits where your roof meets the chimney, and this piece of flashing will protect the mortar joints around your chimney.

Apron Flashing

You must install apron flashing, continuous flashing, where the vertical wall meets the roof, and this flashing guides water onto the roof system.

Roofing contractors recommend valley flashing for roofs with angle changes, which prevents water from pooling in these areas.

Kick Out Flashing

You can also install kick out flashing. Kickout flashing is a specific type of flashing that keeps rain away from the cladding and guides it to the gutter system.

If you are building a house, wall flashing is an excellent way to protect your home from leaks. You install this flashing inside the walls, collecting any moisture that finds its way inside and directing it to a specific drainage area.

Other Flashing Types

roofing contractor shows how to install drip edge flashing

Vent flashing, skylight flashing, and corner flashing are self-explanatory. These roof flashings protect the areas around vents, skylights, and corners.

You should install a drip edge. A drip edge is a thin metal flashing that allows water to drip from the roof’s edge into your gutter. Without drip edges, water can leak behind the gutter and rot your fascia board and roof decking.

How to Install Roof Flashing

The first step for flashing installation is actually to install your underlayment. Then move onto installing your corner flashing, and you will buildup your kick out flashing or step flashing on top of it.

It’s all about layers.

Installers must ensure that all base flashing juts against any vertical surface on your roof. As you get to them, you will install step flashing around protrusions on the roof.

You will need to install expansion joints to help support the long lengths of flashing along your roof’s edge. Install your kick out flashing and work your way up the roof. You should place the flashing base on your roof and seal it to the wall using roof cement or flashing sealant.

Then, place the shingles over the flashing seams to create a neat appearance.

You’ll want to install your shingles over the starter strip and the kick out flashing, fastening with roofing cement or roofing nails. Place your nails high so you can cover them with the next row of shingles. This results in a much cleaner look.

Note: It will help if you cut your flashing and shingles to fit over your roof’s peak. You will want the flashing and shingles to bend over the peak creating a watertight covering. Installers should create a curved look that will ensure a tight and waterproof joint.

Roof Flashing Sealant Types

contractor shows how to install roof flashing using sealant

Acrylic, polyurethane, silicone, rubber, and sealant tape are the most common sealants. Roofing contractors recommend liquid rubber waterproof sealant for the best results. Sealants form a watertight seal that prevents water from seeping into any joints or seams on your roof.

Does Flashing Need Sealant?

Flashing does not work alone. Proper sealant when you install flashing is crucial to its success. The goal is to create a watertight barrier. Sealing the base flashing for your chimney flashing is especially important. Building materials expand and contract at different temperatures, so it is essential to have a sealant that maintains the waterproof seal.

Roof Flashing Material

Flashing is generally a thin material, most often a sheet metal. The most popular flashing material is galvanized steel, and this steel flashing will prevent corrosion. You can also find copper, aluminum, and stainless steel flashing.

Tools For Installing Roof Flashing

It would be best to have several tools and other building materials when installing new flashing. You will need hammer tin snips, circular saw, roofing nailer, roofing nails, step flashing, and corner flashing. You may also need a pry bar if you are removing old flashing.

You should contact a roofing professional if you need clarification on the flashing installation. You can install it yourself, but hiring an experienced professional might be the wisest choice.

Final Thoughts

roof valley on shingle roof with new roof flashing installed

Flashing is incredibly important to your roof installation. Its purpose is to keep your roof dry and prevent water from getting into your home. If water is allowed to enter your roof or home, then you’ll be dealing with critters, rot, and mold that can become dangerous to your family and lead to further structural complications.

However, installing roof flashing can be quite challenging. Consider hiring an experienced roofing contractor to ensure you get the best results, and remember most roofing companies offer a free estimate.

Contact Bay Valley Roofing to get a quote on flashing installation today.

We are roofing specialists that have experience installing all parts of a roof every day, and we are dedicated to informing our customers every step of the roofing process. Whether it be simple repairs, advice, or full replacements, we’ve got you covered.

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