Galvanized flashing is one of the most economical and easy to install types of flashing. Flashing is the last form of protection for your home from water damage. Flashing is used around windows and architectural variances on your roof, areas where vertical walls meet the slant of a roof. Two types of flashing are generally used to redirect water from areas that can receive great damage: step flashing and kick out flashing. Flashing should be installed at the same time you install the roof shingles. For this project you will concentrate on step flashing.
Step 1 – Measure
Galvanized Flashing comes in a roll anywhere from a 4 to 24 inch width, but an 8 inch width is most commonly used for flashing. This provides for adequate protection of the vertical wall and roof seam. Calculate the amount of flashing you will require before you begin the job. Going up and down a ladder is enough work without having to leave to go to the hardware store for more supplies. Galvanized flashing is easily cut with tin snipes.
Step 2 – Install Corner Flashing
You will use two pieces of flashing to create a wrap around a corner. After you have shingled up the side wall, bend the first piece of step flashing in half horizontally. Cut a 45 degree angle from the corner to the bend. Bend the cut angle around the corner, making sure the lower piece lays flush with the roof. Using two galvanized nails, one in each corner, attach it to the vertical wall. Do not nail into the roof. Apply a small line of caulking along the vertical area the next layer of step flashing will be installed. Bend the next piece of flashing in half. Place it flush to the side wall of the corner where you just installed the first piece of flashing. Bend the corner at a 45 degree angle over the line of caulking to completely cover the first corner bend. Attach the piece with one galvanized nail to the side wall.
Step 3 - Install the Layers
This process is somewhat of a layering or weaving application. You will install several shingles to one piece of flashing. The flashing will go over the bottom shingle and under the top shingle. Install a shingle, and then align the galvanized step flashing to layer just over where you nailed the shingle. The flashing should over lap the shingles as to cover the roofing nails used to install the shingles. This layering process continues up the side of the vertical wall: one shingle, then one piece of flashing, then another shingle. Make sure to only nail the flashing to the vertical wall. The less openings you create for water to enter the roof the better. While water does drain down, wind can cause water and debris to blow up and under the shingle.