Attic ventilation (electric fan vs ridge vents)

Old 01-29-19, 08:37 PM
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Attic ventilation (electric fan vs ridge vents)

Hello All,
We are about to have the shingles replaced on our home and I would like a few thoughts on attic ventilation. The home is 3000sq ft and 20 years old, located in south Alabama, btw. We are going back with a tan colored architectural shingle.

The roof is mainly a hip roof with exception it has a gable roof over the garage/bonus room (bottom right in image).

The home has two electric attic ventilators but I would like to go back with ridge vents. The problem is the two ridges are only about 12 ft in length and the contractor doesn't feel that would be sufficient. I agree considering the gable attic is very small and it would offer virtually no ventilation for the rest of the home. Consequently, he is encouraging me to stay with the electric ventilators.

Is there any way to calculate how much ventilation I would need for ridge vents? Otherwise, do you have a better alternative then two electric ventilators?

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Old 01-30-19, 04:54 AM
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Yes, there is a way to calculate. Look up the specs for the ridge vent you are considering and see how much open area it creates per linear foot. I'm with your contractor though and don't think it will be adequate. There are also recommendations on attic ventilation based on the attic size.

Personally I hate ridge vents. I've seen them leak way too often. I much prefer mushroom style vents up to about 12:12 pitch especially when you can place them on the back side of the roof out of view but as close to the ridge as possible.
Old 01-30-19, 11:36 AM
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Unlike Dane, I prefer ridge vents but, as you've seen, they don't work well with the short ridge of a hip roof. I would go with roof vents placed as reasonably high on the roof as you can (I'm also not fond of attic fans for the propensity for drawing house air into the attic).

What do you have on the intake side of the equation?
Old 01-30-19, 12:50 PM
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I am on the ridge vent side. No moving parts and not sucking from the interior. But like Stickshift asks, it has to be balance with proper intake flow.
Ridge vent companies design for hip roofs too
Hip Ridge Vent - Air Vent, Inc.

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