We’ve seen quite several different techniques for roof ventilation across the Greater Portland area including artistic roof ventilation, roof ventilation overload, and the use of additional can vents.
During an inspection of a Beaverton Condominium complex, we noticed the use of can vents placed low on the roof for intake instead of having intake cuts below the roof line.
The question is, does this roof ventilation system actually work? Yes, however it’s not the proper use of can vents. Can vents are designed for the outtake portion of your roof ventilation system. It would be like using a fork to flip burgers on the grill instead of burger spatula; it works, but it’s not the most efficient use of your cooking toolbox.
What we would do is either put in a soffit vent or what we call a SMART vent. A soffit vent allows outside air to enter the attic at the lowest point of the roof—along the underside of the eave. They’re most effective when used in conjunction with a continuous ridge vent. A SMART vent is, a tapered, under shingle plastic product designed for installation along the soffit edge of the roof or the facing edge of dormer rakes and goes virtually unnoticed. It allows air to flow freely through the 1″ roof decking slit providing more than adequate soffit ventilation to maximize ridge vent effectiveness. (source http://www.dciproducts.com/html/smartvent.htm)
For more information about having an energy efficient roof please visit our RL Green Contractor page.