How to install attic vents

Installing attic venting. To determine your house’s venting needs.

Check local building codes before adding vents. Roofing suppliers sell a variety of soffit vents: individual units and plugs, continuous strips, or perforated soffit boards.

To install a vent unit, make a template of the side of the vent that will go into the soffit. Trace its outline on the soffit between two lookout beams (look for the heads of the nails attaching the soffit to the lookouts). Drill starting holes in the corners of the outline. Use a saber saw or a keyhole saw to cut a hole: screw the vent in place.

To install a vent strip, snap a chalk-line 3 inches in from the outer edge of the soffit. Snap a second chalkline separated from the first by the width of the inside part of the strip. Drill starting holes: saw along the guidelines and between them on both sides of each lookout. Remove the freed soffit sections. With a hammer and chisel, cut along the guidelines into the soffit pieces still nailed to the lookouts; pry off the pieces. Press the vent into the channel; nail it to the lookouts. If necessary, chisel into the lookouts so that the vent seats properly.

To install a perforated soffit board, use a pry bar to remove the old soffit (you may first have to remove the fascia board and the rear molding). Nail the new soffit to the lookouts.

Ridge, gable, and roof vents Whether or not your house lends itself to soffit venting, rooftop vents are essential. Ridge and cupola vents are most efficient, but installing them is a job for a professional.

Rectangular or triangular louvered vents can be fitted into both end walls of a gabled roof, as close to the roof ridge as possible. To install a rectangular vent, draw a rectangle on the inside attic wall ‘A inch longer and wider than the inside part of the vent. Drill corner starting holes; saw out the opening. If you cut through a stud, remove about 11/2 inches of it above and below the opening to accommodate two 2 x 4 headers.

Nail the headers to the studs on both sides of, and above and below, the opening. Apply roofing cement to the vent’s outer lip; from outside, fit thevent, louvers down, into the opening. Nail the vent’s inner lip to the headers. Caulk the vent’s outer edges with roofing cement.

For a triangular vent, trace and cut an opening just below the ridge beam. Saw 11/2 inches off the top of any stud below the opening; nail a 2 x 4 header to the cut studs. Cut two more lengths of 2 x 4: nail them to the rafters on either side of the opening. Fit the vent into the opening as described.

Position a roof vent inconspicuously. Measure from the center of the location to the roof ridge and to the nearest side edge of the roof (minus overhang). With these measurements, locate the vent’s tentative center point inside the attic. Draw a line from rafter to rafter through this point. At the midpoint of the line, drive a nail through the roof. Find the nail tip on the roof; use it as a center point to draw a circle equal in diameter to the vent hole.

Drill a starting hole on the circle; saw an opening. In the attic, frame the opening with two 2 x 4 headers nailed to the rafters. On the roof, place the vent over the opening. Draw a line around the base; remove the shingles within the marked area. Caulk the the vent’s base, place it over the opening, and nail it to the sheathing with roofing nails. Restore the shingles around the vent. Most attics require two roof vents (one, if the vent has an electric fan).