How to Build Overhangs When Using Trusses

Determine the length of the overhang -- usually 6 to 36 inches wide. Measure the length horizontally. Use this figure as the measurement for fabricating the extensions.

Set up the ladder or scaffold to work at the bottom edge of the roof. Check to ensure the ladder is on a stable and level surface.

Remove the fascia board covering the trusses and other trim with a pry bar and hammer. This enables you to see into the attic of the house. Count the trusses to determine the number of extensions required for the overhang.

Mark off on the 2-by-4-inch lumber two times the length of the overhang. For example, make a mark at 48 inches for an overhang with a 24-inch length. The extra 24 inches is the part of the extension that’s secured to the truss.

Cut the wooden extensions from the same size lumber used for the truss chords, such as 2-by-3 or 2-by-4-inch lumber. Select straight construction grade lumber. Use a lumber with smaller dimensions if necessary depending on the opening. Use a circular saw to cut the material.

Measure 24 inches, starting from the bottom end of the truss top chord up toward the truss’s peak. The top chord is the diagonal component. Have a helper work from inside the attic if necessary. Mark the line for the extension on the side of the top chord for each truss. Position the extension parallel to the top chord of the truss. Place 16d nails every 8 inches. Stagger the nails from top to bottom. Repeat this process for the other trusses.

Nail 1-by-6-inch fascia board to the tail of the extensions. Secure the sub fascia board from the underside of the fascia to the side of the house. The length of the board is the same as the overhang. Use screws to secure the fascia board in place.

Cover the top surface of the overhang with plywood the same thickness as the roof or 1/8 of an inch thicker. Use screws to secure the plywood to the extensions.

Apply roofing felt over the plywood. Secure to the surface with galvanized roofing nails. Follow the manufacturer’s instructions for installing shingles or other another covering to the overhang. Match the existing roof covering.