My roof already had the ridge and soffit vents and gable vents. Does it need attic fans/rotary turbines as well? I heard that I should close off the gable vents to let the ridge and soffits do their job.

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Many building codes require at least 1/300 of the attic area in free openings for ventilation when cross ventilated, which it sounds like you have. If not cross ventilated, you need 1/150 of the area. Be sure your soffit vents are not obstructed by insulation. If the ridge and soffit vents meet this requirement without the gable ends, you might consider closing off the gable ends.

My guess is they were put there for a reason and you will not have adequate free area without them. I don't think you get extra credit for turbine vents though they can move more air because they don't move much air in still conditions. You should avoid mechanical ventilation if at all possible IMO.

  • "you should avoid mechanical ventilation" - does it mean attou cic fans or turbine fans as well? if you don't mind - please add your reasoning. thanks!
    – webwesen
    Commented Aug 27, 2013 at 13:19
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    I simply believe in not needlessly adding devices that can fail except when necessary. Any mechanical device can fail. Certainly a static screened opening can fail too, but it's much more reliable than motorized devices. As turbine vents have no motors, I would prefer them over active fans, but static openings are still better where possible IMO.
    – bcworkz
    Commented Aug 27, 2013 at 18:40

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