How to Install Roof Flashing against a Brick Wall

Lead Image
  • 5-10 hours
  • Intermediate
  • 500-1,000
What You'll Need
Metal roof flashing
Chalk line
Circular saw
Metal cutting scissors
Clear silicone caulk
Caulking gun
Circular saw

Metal roof flashing can be use to seal gaps between roof walls. It is commonly used in two-story and side-split houses. These kinds of houses often have a roof that butts against a wall. Metal roof flashing is a galvanized sheet metal bent at right angles, with about eight to 12 inches on each side of the angle. You can hire a professional to install it against a brick wall, or you can do it yourself.

Step 1 - Choose What Kind of Metal Flashing You Need

You have to first decide what size of flashing you will use. While 8-inch flashing usually works well for most purposes, you might want to use another size.

Step 2 - Install Base Flashing

Now, install the base flashing. This can be under shingles or over metal roofing material. You have to install the roof side of the flashing either under the last layer of shingles or over the roof materials if the roof runs flat up against a brick wall.

Step 3 - Flashing Angled Roofs with the Step Method

upper dormer windows on a roof

You can use the step method to flash an angled roof. You need step flashing, which is metal flashing that is in an “L” shape. These are usually of shorter length than the usual. A six-inch length would do. In this method, a row of shingles overlaps each previous row of flashing. Start at the bottom of the angle and work your way upward.

Step 4 - Caulk Seams and Exposed Nailhead

Now you should caulk any exposed seams, where flashing meets another piece of flashing. Also caulk any exposed nail heads.

Step 5 - Install Counter Flashing

caulking around flashing surrounding a chimney

Counter flashing is necessary to prevent water that runs down the outside face of flashing from going behind the base flashing. Use your caulking gun to caulk a straight line above the back of the base flashing. Cut a slot of about 1.5 inches into the brick with a circular saw and masonry blade. The will allow the overlapping flashing or counter flashing to slide into the slot. Now seal the slot with a caulking gun after the flashing is installed.

Step 6 - Install through-wall Flashing

Through-wall flashing is necessary to redirect moisture that has penetrated the veneer back to the outside. Install it through the entire thickness of the brick veneer. Sometime the through-wall flashing can be the same as the counter flashing.

Step 7 - Flashing Your Chimney

If you have a chimney, it presents its own flashing issues. Flashing will need to be used at the base, the intersection of the chimney with the rood, and at the chimney crown. Flashing must be used where the foundation meets the brickwork. It should extend from the brick veneer wythe, through the brick’s exterior face, and end in a mortar joint in the interior wythe.