Roof Flashing Installation: How to Bend Chimney Flashing

What You'll Need
20 or 40 ounce sheet metal flashing
Sheet Metal Brake
Brake mounted slitter
Tape measure
Speed square
Scrap piece of wood

Installing chimney flashing requires some skill, specialized tools, and attention to detail. The flashing around the chimney is one of the most common places for roofs to begin leaking, and if the chimney flashing is not bent, and installed, correctly then the chance of roof leakage is tripled.

Step 1: Measurements

The first thing you need to do is to take measurements of the lengths that you need for the chimney flashing. Add 10 inches to allow for the overlap. Then, find the angle using the level and a protractor.

Step 2: Preparing the Flashing

Next, cut the flashing, using the brake mounted slitter, to the length that you had written down. Mark the flashing to show where the bending needs to occur. Place the chimney flashing into the sheet metal bender, or break, and align the marks that you have made up to the end of the clamp. Tighten the machine down by using the lever on the side. Then bend. Check your work periodically, using the protractor to make sure it has been bent to your specifications. Also, check by placing the flashing alongside the roof, to make sure that a secure fit has been made.

Step 3: Overlapping

After the chimney flashing has been bent, use the brake mounted slitter to cut in 5 inches from each end of the chimney flashing, giving you the flaps on the ends to use as overlapping material.