eave: Secure F-channel to the wall and to the inside of the fascia board, level with each other. Cut out back of channel to fit around rafters, if needed. With closed Eave: Substitute J-channels for the F-channels. Secure all channels in the center of the nail slots, 12" on center. Installing Soffit Measure the distance between the inside of the inside and outside trims. Allow 1/4" per side for expansion and cut the panels to length. Insert panels into trims. For eaves over 18" in width, you will need to install intermediate nailing supports to keep the soffit from sagging. Interlock panels as you would vertical siding. Closed soffit can be secured every 12" on center. When fascia panel is not being applied, use an F-channel or J-channel at corners of the overhang to properly finish the installation. When soffits meet at a corner, the joint can either be diagonal (mitered) or square (both illustrated). Both methods are made with J-channel or H-channel. NOTE: Ventilation Requirements: Proper attic ventilation is important for any home. Consult the local building code for the appropriate requirements for a specific geographic area, and use vented soffit or other vented products as required. Installing Fascia Install an undersill trim at the top of the fascia board. Measure distance from the bottom of the F-channel to the top of the undersill trim, and then subtract 1/4" for clearance. Cut panel to width. Perforate the cut edge using snap-lock punch approximately every 8", ensuring the "tabs" face