How to Install Flashing Around a Fireplace With a Metal Roof

Measure each side of the chimney with a tape measure. Write these measurements down so you know how big to cut the flashing. Add 12 inches to each measurement so you will have room to bend and fold the flashing around the chimney.

Remove the old chimney flashing by gently prying up the metal roofing tiles at the base of the chimney with a pry bar and a hammer. Remove the old nails by prying them up with the claw of the hammer. Pull the old flashing away from the chimney.

Wrap the base of the chimney with synthetic underlayment. Cut strips for each side. The underlayment should extend approximately 1 foot onto the roof and at least 6 inches up the side of the chimney.

Apply a layer of construction cement along the edges and press them along the roof and chimney to seal the edges.

Cut out strips of flashing to your required measurements using metal snips. The strips need to be approximately 1 foot wide.

Lay the first strip of metal flashing flat on the roof in front to the chimney.

Mark the width of the chimney on the flashing and cut down 6 inches into the width of the flashing with metal snips. Bend the inside of the cut flashing up so that it goes up the side of the chimney while the remainder of the flashing lies flat on the roof.

Nail the first strip of flashing into the chimney using roofing nails. Continue with the other four sides of the chimney.

Apply a heavy layer of silicone caulk to all edges of the flashing. Allow the flashing to dry overnight and nail the metal roofing back into place.