A.Bill Rose responds: We’re conducting research at the University of Illinois to answer these questions. The advice below is based on recent literature and my experience in a temperate climate (hot summers and cold winters).

Vents do keep attics and cathedral ceilings cooler. With the sun shining, the air temperature in a vented attic may be 10°F to 15°F cooler than in an unvented attic. So the temperature argument for ventilation holds in most of the U.S. The other main reason to ventilate is to prevent moisture accumulation in the attic or roof system. The...

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