Originally Posted By: khayden
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I am looking for recommended levels of attic ventilation.
I am looking for recommended levels of attic ventilation.
Originally Posted By: Ryan Jackson
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I think it is 1 square foot of opening for every 150 square of attic space. Anyone confirm?
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Ryan Jackson, Salt Lake City
Originally Posted By: mbailey
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Keith - Typically 1 square foot of free vent area is required for every 300 square feet of attic floor area.
Ryan - I believe the 1/150 is for crawlspaces with no moisture barrier in place... i.e. bare soil
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Mark Bailey
Stonegate Property Inspections LLC
Ponca, NE
Originally Posted By: jpeck
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1 sf of free vent area per 150 sf of attic area.
With an exception allowing 1 sf of free vent area per 300 sf of attic area when at least 50% of the free vent area is in the upper half of the attic.
This requires more free vent area for soffit vents only ventilation than is allowed when there is a ridge vent, gable vent, off ridge vent, etc., providing sizes are met.
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Jerry Peck
South Florida
Originally Posted By: mbailey
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Jerry,
I believe what you are saying is 1 SF to 150 SF when no undereave venting is present and/or the ventilation system is unbalanced?correct?
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Mark Bailey
Stonegate Property Inspections LLC
Ponca, NE
Originally Posted By: jpeck
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Mark,
No. The requirement is 1 sf free vent area per 150 sf of attic space.
Then there is the exception which allows the free vent space to be cut in half, and that is if half of the vent is high and half is low, to create a gravity low of 'hot air rises' up and through the attic.
You could have all soffit vents (which is what is done down here), and that requires 1 sf free vent area per 150 sf of attic space.
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Jerry Peck
South Florida
Originally Posted By: mbailey
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I am on track with you now Jerry. Thanks
Heat must have muddled my brain today and the ole noggin just did not want to negotiate through comprehension.
Had 88 degrees and 40 mile an hour winds today, it is a little early here for the heat ? should be low 60?s. Weather must have sucked a little more out of me than I thought.
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Mark Bailey
Stonegate Property Inspections LLC
Ponca, NE