DIY Triangular Attic Vent

Determine the pitch of the gable roof peak and decide on a depth for a gable roof vent. Size the vent according to the roof space; get a deeper one for a large roof or a small peak vent for a smaller roof. Buy either metal or vinyl, depending on your preference and the type of roof, but get one that will complement your exterior when installed.

Mark the bottom for the vent and remove siding and any fascia or trim boards in the area with a pry bar Use a circular saw to cut out sheathing in the vent area, but set the blade depth carefully so you do not cut into rafters or studs. Work from scaffolding, if possible, to have a stable platform while cutting out for the vent and installing it.

Put a bead of construction adhesive or strong caulk around the edges, on the rafters and studs framing the opening. Fasten the vent sides to the rafters and studs with screws, which should come with the vent; use galvanized screws and drive them with a screw gun, into the framing through the holes in the installation flaps around the edges of the vent.

Replace the fascia or trim on the angled rake edges, putting it over the installation flaps on the vent. Add trim on the horizontal bottom of the vent, cut on the ends to conform to the slope of the roof. Put a cove molding around the vent, if desired, to further secure it and make it more decorative.