A.Paul Fisette, director of Building Materials and Wood Technology at the University of Massachusetts Amherst, responds: In order for a ridge vent to exhaust, you need a pathway and a reliable driving force. Both a single-sided and a double-sided ridge vent provide a pathway, so the important question is this: What is the main driving force that pushes attic air up and out of the ridge vent?

While wind direction can induce roof venting — and it's been shown that even soffit-only venting can draw air out of roofs — most often the answer is the buoyancy of the attic air. If there is a fair amount of heat loss from the house into the attic, then the buoyancy of the warm air rising causes it to escape at the highest point, the ridge.

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