Install Chimney Flashing, Uniflash

Install Chimney Flashing, Uniflash

Here are easy instructions for chimney flashing installation . These instructions are written for shingles, but the process is the same regardless of whether the roof has wood shakes or is slate, tile, or one of the new eco-roofing systems.

Home experts recommend that you install chimney flashing when any new roofing is put on, since flashing should be as long-lasting as the new roof system.

Before you install chimney flashing, read this to understand how flashing and counter flashing work together. Most chimneys today are built on a foundation that is separate from the home, and need to have flashings that can flex independently, without breeching the important water seal that the flashing forms with the roofing.

The first part of these instructions shows flashings that are incorporated with the shingles, and are fastened to the roof, making sure that they are not fastened to the chimney at any point, leaving the upper parts free standing.

The second part discusses counter flashings and how they are used to steer rainwater and melted snow safely down the roof. Counter flashings are affixed to the chimney, leaving just the bottom part free-standing. Read these instructions to install chimney flashing efficiently and get the perfect result!

Step 1: Chimney Flashing Installation

Apply shingles up to and along the length of the chimney base, to a place where the tar-line of the shingles is within 4 inches (100 cm) of the base. Cut off the excess shingle material as needed.

Step 2:

Center the base flashing across the length of the chimney, extending 3 to 4 inches beyond each end. Remove a notch from each end, and bend the tabs around the chimney sides. Nail the base flashing securely, making sure the nail heads will not be exposed, and will be underneath the next row of shingles.

Step 3:

Remove the notch from the step flashing and bend the tab toward the front of the chimney. Usually, step flashings are used to terminate a row of shingles at a dormer, wall or chimney, and begin just below the tar-line.

The next task is toplace the step flashing against the chimney and nailing it to the roof at the point where the nail head will be protected by the following shingle.

Step 4:

The next step is to repeat the step flashing installation on the on the other side of the chimney and nail it into place. Then cut the shingle material for the next row so that it lines up with the shingles below and covers the step flashings leaving a gap of about 1/4 to 1/2 from the chimney to form a water drainage trough. The shingles that are installed on the other side of the chimney should be installed so they also form a trough for water drainage.

Step 5:

Continue installing the step flashings, as well as shingle material, on each side of the

chimney until the shingles clear the back of the chimney, making sure that the shingles line up with the other side of the chimney. When nailing these shingles, a good rule is to position the nail about 1 above the water slot. This helps guard against weathering and corrosion of the nail.

Step 6:

Cut and fit the final step flashing pieces to fit around the back of the chimney and on each side of the chimney and set them in place. Its a good idea to set the pieces in a roof cement before finally nailing down.

Step 7:

The next step in installing the chimney flashing is to cut the next row of shingles to fit the back of the chimney. This fit should be close, with practically no gap.

Step 8:

Now, you can complete your installation of the next row of shingles along the back length of the chimney, Nailing them in place.

Step 9:

Find the center-point and affix the cricket flashing along the back side of the chimney, letting each end go beyond each corner by 3 to 4. Mark this spot. Trim each end up to the mark you made, and form the tabs around the sides. Nail the bottom of the cricket to the roof.

Step 10:

The shingle installation is nearly complete. Inspect your work to make certain there are

no gaps where your work can be ruined by leaking ice, snow and rain.

Step 11:

Install Chimney Flashing, Uniflash

Now, lets move on to counter flashings. Install counter flashing by lining up the top of the flashings in straight lines, around the chimney perimeter. For both sides, use a temporary marker to mark the tops, making sure you have a small space at the bottom near the shingle line for rain flow.

Align the tops of both the back and front counter flashings with the top portion of the side counter flashings. Mark for reference. Move on to the next step, while setting the counter flashings aside for now.

Step 12:

The next step in completing the chimney flashing installation is to notch the counter flashing ends and bend them around the chimney sides. We recommend that you cut the tops evenly with the chimney corners. Now, form the tabs around the sides. This step helps guard against metal warping when bent. Now, using masonry fasteners, fasten the counter flashing to the chimney, making sure the metal fits snugly against the brick.

Step 13:

Position the side counter flashing material along the mark you made earlier, and cut evenly with the counter flashing on the front. Notch the back corner and form the tabs toward the back. Add 2 or 3 additional masonry fasteners. Side counter flashings sometimes look wider, since they are angle-cut. Keep the tops in a straight line for the best appearance and performance results.

Step 14:

The final step to install chimney flashing is to mark the rear counter flashing evenly with the corners of the chimney and position along the mark you made. Install additional masonry fasteners.

Re-examine the tops of each of the four counter flashings to make sure you can see the V notch. Use caulking material on all of the four counter flashings alongside the V as well as at each corner. Make sure there arent any spaces where water can enter and cause damage.

Click link for a detailed PDF on chimney flashing installation instructions.

Download Flashing Kit brochure.


26835 West Seven Mile Road

Redford, Michigan 48240

888.814.3721 313.531.5630

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