ridge and soffit ventilation

Old 09-22-09, 06:30 AM
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ridge and soffit ventilation

We're having our roof redone from cedar shingles to composition and wondering if ridge or power vents provide better ventilation. The one power vent we have doesn't do the job. We've also read different requirement for soffit ventilation from 1sq ft of ventilation for every 150 - 300 sq ft of attic space. Our attic has 2359 sq. ft. of area. House has a hip roof, the main ridge line is 64' long and 38' of ridge over the garage. There are currently 11 14x6" soffits providing 924 sq. in. of ventilation. Do we need more soffits if we have a ridge vent installed?
Old 09-22-09, 07:02 AM
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Hi t, power vents have issues, like de-pressurizing the attic and pulling conditioned air out of the house, or only functioning in a certain temp range which may turn them off too soon and not function at all in winter months when warm moist air needs to be vented. Not to mention the energy they use to do their job. Passive venting is 24/7 so taking the opportunity to install enough when you can makes sense.

I prefer the 150 number and the ridge venting will give you high and low venting. Yes, I would add some additional soffit venting as the vents never deliver 100% of their area and hip roofs tend to have deep corners that are hard to vent. Air seal all plumbing, electrical, and chimney air leaks and check areas around drop ceilings to see if they are air sealed as well. Basically, you don't want inside air getting into your attic, moisture and energy loss. All recessed light fixtures should be air tight and IC as well. And make sure all bath and kitchen vents are vented to the outside and not into the attic or soffit area.


Last edited by Bud9051; 09-22-09 at 07:04 AM. Reason: addition

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