Question: We are contemplating a new roof on our 35-year-old home (2,900 square feet), which currently has a hip roof. We have received two different opinions. One roofer recommends no ridge vent and wants to use power and drip vents. The other says to use ridge vents and drip vents. We can find nothing on the drip vents and are at a loss as to what to do. We have two vent fans, one large and one small. We prefer not to use any electrical vents if possible. Any suggestions?
Answer: The purpose of roof venting is to move as much hot or humid air out of the attic as possible, replacing the vented air with fresh dry air. Years of research indicate that a ridge-vent system, incorporated with soffit or eve vents (drip vents), is the most efficient and effective choice. Electric fans, turbine vents, canned vents and gable vents can be used, but the ridge vent is, in my opinion, superior to any of these vents.
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The ridge is the peak of a gabled or hip roof. On a gabled roof, it extends the length of the home. A hip roof has a ridge that is much shorter, owing to the four or more hip sections that intersect the ridge. Depending on the pitch of the roof, the length of the ridge of a hip roof can be as little as one-quarter the length of the home. A shorter ridge means you have less area to work with when trying to obtain optimum ventilation. With a minimum standard of 1 square foot of venting for every 300 square feet of attic-floor space, trying to obtain half of that venting from the ridge the situation becomes complicated.
A solution would be to vent the hip rafters wherever possible. Because the ridge and hip vents are open to the weather, a low-profile vent should be used. A hip vent and a drip-edge vent can be seen on the Web at www.airvent.com/professional/products/ridgeVents-hipridge.shtml.
In place of the drip vent, "Cor-a-Vent" makes a low-profile intake vent, which can be installed, low, near the edge of the roof and shingled over to conceal the vent from view. The "In-Vent" system (www.cor-a-vent.com/in-vent.cfm) and a venting calculator (www.cor-a-vent.com/v300.cfm) can help you determine the amount and type of venting you need.
(Dwight Barnett is a certified master inspector with the American Society of Home Inspectors. Write to him with home-improvement questions at C. Dwight Barnett, Evansville Courier & Press, P.O. Box 286, Evansville, IN 47702, or e-mail him at d.Barnett(at)insightbb.com. Please include a SASE with your questions.)
