Installing Continuous Flashing

Because continuous flashing is less robust than step flashing, Mike backs it up with 12-inch flashing tape. He bonds 6 inches of the flashing tape to the wall and 4 inches onto the roof sheathing.

The remaining 2-inch portion of the flashing tape folds over on itself and bonds to the roof underlayment. The joined pieces then fold toward the wall.

Mike tacks the joined pieces to the roof with staples.

One of the few details provided by the code for continuous flashing is a 4-inch minimum for both the roof and the wall legs. Mike increases that to 5 inches to gain enough coverage for many types of siding. He makes a double folded J-roll along the edge to eliminate sharp edges that could cut the shingles.

With this method the shingles lay on top of the flashing. The J-roll helps to divert water back onto the flashing where it drains down the slope. A bead of roofing cement can also help. Note that the J-roll might telegraph a hump through thinner 3-tab shingles.

To further protect against water incursion with continuous flashing, Mike back-flashes with two strips of 4-inch flashing tape. First he scores the middle of the first strip.

Then Mike removes the backing from half of the first strip ...

… and bonds it to the outboard edge of the roof leg of the continuous flashing

Mike scores the second strip down the middle ...

... then peels the release backing from the strip stuck to the flashing, and the backing from half of the second strip.

Then he bonds the sticky faces of the two pieces of flashing tape together.

Next, fold the flashing tape back on top of the continuous flashing.

Remove the remaining release sheet from the flashing tape and bed the shingles into the adhesive as each one is placed on the roof. The back-flashed tape helps block water from reaching the underlayment.

Or you can flash over the shingles

Mike avoids driving fasteners through the roof leg by using clips made from scraps of flashing metal to secure the outside edge. The clips are folded in the middle and fasten through the roof shingles in line with the outside edge of the continuous flashing every 16 inches or so.

Next Mike sets the continuous flashing in place over the clips.

The wall leg is attached to the wall with nails or screws.

The final step is bending the clips over the edge of the continuous flashing. As with the under-flashing method, flashing tape between the continuous flashing and the shingles can provide added protection.

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