How to Flash a Roof to a Wall Using Vinyl Siding

Install the corner flashing into the inside corner where the eaves of the roof meet the wall of the house on top of the felt paper moisture barrier for the siding. This flashing is shaped like an L. Liberally coat the back side of the flashing with silicone adhesive and press it firmly into place. Overlap the horizontal sections by at least 2 inches and cover this with silicone adhesive as well. Cut the pieces to length where necessary with the shears.

Mount the inside corner pieces for your chosen vinyl siding. These are provided by the manufacturer depending on the type of vinyl siding you have chosen. Mount them in place on top of the flashing. Nail them in place with the manufacturer recommended nails and run it down the length of the wall where the roof meets the wall.

Place the vinyl siding up the wall to the underside of the corner piece. Vinyl siding works by each upper piece hooking up and under the lip of the piece below it, like a J that leans toward the left slightly. For the last upper row, the vertical section of the J needs to slide up and under the lip of the corner piece, holding it in place. The soffit panels install similarly, with the corner mounts holding the pieces in place into the inside corner.