How to Use Ridge Vent for Ventilating an Attic

Check for soffit vents. These vents will show up as slots in the underside of the soffit. They may also be continuous strips of vinyl that have screen-like openings all along the outside edge of the soffit. There may also be soffit vents that look like heating and cooling registers attached to the soffit. If there is no way for air to flow into the soffits, soffit vents will have to be added.

Check in the attic for openings along the top of the long walls of the building. These openings will be at the back side of the soffits right at the top of the wall. Look in between rafters, or trusses, for narrow openings created between the tops of the walls and the tops of the rafters or trusses. If there are no openings between the rafter or truss tails then “bird stops” have undoubtedly been previously installed. These bird stops will need to be removed before air will flow from the soffits to the ridge vent.

Check for unobstructed open space from the openings at the back of the soffits all the way up to the ridge of the roof. Air needs to flow from the soffits and along the underside of the roof for the best ridge vent efficiency. In many cases attic insulation may be right up against the underside of the roof and this will block the air flow to the ridge vent. When this is the case consider installing Styrofoam products designed to fit between the rafters and hold the insulation away from the underside of the roof while creating a raceway for the air to flow through.

Remove the existing shingles covering the ridge, (if retrofitting an existing roof, otherwise on new construction install the ridge vent once the shingles are installed to the slot along the ridge), and cut a 1 1/2 inch wide slot in the roof sheathing the length of the ridge. Cut the slot to the width specified by the ridge vent manufacturer. Center this slot on the ridge. Set the circular saw blade to only cut the thickness of the sheathing, and not the rafters or trusses.

Center the ridge vent over the slot cut in Step 4 and nail into place through the holes in the vent material. Make sure nails are long enough to go through the shingles beneath the ridge vent and into the sheathing.

Cut away the underside of ridge vents that require the underside to be removed at the ends of the ridge, and nail down the ends for a tight seal.

Nail end caps into place at the ends of the ridge for ridge vents that use end caps.

Cut new ridge cap shingles by cutting off all single tabs while the shingle is upside down. Angle the cuts slightly to minimize their exposure once installed. Cut the back side of the shingle and then bend and break it.

Snap a chalkline five inches down from each side of the ridge vent.

Set the ridge cap shingles from each end working toward the center. Lap them over the ridge vent in the same fashion as for a standard roof. Keep nails in 1 1/2 inches from the sides.

Install a 5 inch wide strip where the ridge caps from the two sides meet.

Apply dabs of roofing cement to the nail heads.