How To Install Roof Flashing (Step By Step)

Roof flashing is a crucial element in your roofing system, ensuring water diversion from seams and joints. Learn how to install roof flashing for effective waterproofing.

Unfortunately, these items can crack and break due to extreme weather or deteriorate as they age. But installing roof flashing is not complicated, making it a straightforward job to tackle if you want to save some money on roof repairs. 

This helpful guide takes you through each phase of installing roof flashing so you can ensure your home is functional and protected. 

The Many Types of Roof Flashing 

Naturally, there are many roofing material types, making it necessary to have several flashing types and sizes to suit any roofing system. In addition, you can find flashing in multiple materials including stainless or galvanized steel, copper, or aluminum options.  

The types of flashing you may require for your home based on the roof design include: 

• Base flashing 
• Continuous flashing
• Counter flashing 
• Drip edging 
• Kickout flashing 
• Skylight flashing 
• Step flashing 
• Valley flashing 

In addition, flashing will come in multiple sizes to ensure optimal coverage of roofing materials. It should extend beyond the shingles or tiles to provide the protection your roof needs from water. 

If your home needs flashing installed, you should pay attention to these areas: 

• Where the roof joins the side and front walls of the house 
• Valleys and dips in the roofing structure 
• Protruding fixtures, like skylights and vents
• The roofing edges 

The Steps to Follow When Installing Roof Flashing 

If you want to tackle the job of installing roof flashing on your home, this guide will help you work through each step. 

Step 1: Gather Your Tools and Supplies 

Once you are on the roof, you don’t want to worry about traveling up and down for tools or supplies. Therefore, having everything within reach will make the job easier. So, gather these tools and supplies, so you are ready to tackle this job.  

• All necessary flashing pieces 
• Hammer
• Pry bar 
• Roofing caulk 
• Roofing nails 
• Tin snips 

Step 2: Clean the Area 

If you are installing flashing on a new roof, ensure there is no debris around the working area. Alternatively, if you are replacing old materials with new flashing, you will have to take the time to remove the broken pieces and prepare the space for new flashing. 

Any obstructions can affect how well the flashing works and waterproofs your roof. Therefore, the area must be clean and free of old nails or screws, or other roofing materials. 

Step 3: Install the Underlayment 

Everything on the roof requires underlayment for additional protection, including flashing. This underlayment can be waterproof tar, felt material, or adhesive and non-adhesive synthetic sheets. 

Step 4: Install Flashing Pieces On the Corners First 

Water will run downhill from the top of the roof. Therefore, for a proper installation, you must install all materials starting at the bottom and working up. This way, water cannot get underneath any roofing materials and will continuously flow over all the layers. 

The corners need step flashing first before moving on. This phase requires you to bend it around the roofing corners and secure it. Then, attach it to the sidewall with galvanized roofing nails in each top corner, but leave the bottom edges that sit on the roof. 

Remember that a house’s foundation will continuously move, so you don’t want to attach flashing to both the side wall and the roof. Otherwise, you risk it cracking or breaking with movement from fluctuating temperatures. 

Step 5: Apply Roof Caulking to Seal the Overlapping Areas

Before securing the second piece of corner flashing in place, apply waterproof sealant where the two pieces overlap. This phase helps prevent water from penetrating between flashing sections. 

Step 6: Install the Kickout Flashing Pieces 

The kickout flashing will be at the base of the roof in the corners. Because you will be working from the bottom up, this is the next phase of properly installing flashing. The bottom corners will have to handle substantial water flow, so these sections are critical for a proper installation. 

Eventually, your shingles and additional flashing pieces will cover these first sections, providing the best water barrier possible and directing water away from the corners and seams. 

Step 7: Overlap and Weave the Flashing With the Shingles

As you work your way up to the top of the roof, the flashing pieces will alternate and weave over and under the shingles. 

This pattern provides the best protection since a single piece can fail and cause significant water leaks. However, with multiple alternating pieces, if one section fails, it helps direct water to the section below, minimizing the chance of water damage. 

Step 8: Install the Top Pieces 

Once you reach the roof’s top, it will peak, requiring you to install a custom flashing piece that covers this angle. Depending on the flashing size, you can use tin snips to cut it so that it lays flat against the roof’s peak. 

Then, secure it in place with one roofing nail. 

Step 9: Apply the Roofing Caulk to Seal It 

Finally, you will need to apply waterproof roofing caulk to seal the top and eliminate the chance of water getting under the flashing. This step completes the flashing install, preparing your roof for new shingles. 

Proper Roof Flashing Installation For Extending the Life Of Your Roof 

When you have a proper installation of your roof flashing material, you are helping to extend the life of your roof. In addition, there will be less chance of a roof failing during extreme weather when all materials are in place and secure. 

Water damage can be one of the biggest problems that appear with a roofing system, making flashing a necessary item for every home, regardless of size or design. Installing new flashing isn’t difficult when you follow these nine easy steps. This way, you can save yourself some money and protect your home from water.