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wrote:

Choreboy wrote:

I'm about to add ridge vents because they are the most cost-effective method.

Moreso than a gable vent with the same free area?

That's what I've read. If you have rige vents and soffit vents, you
have several feet of height for convection, and your air movement is
spread out under the roof.

I have a complex hip roof with no soffit vents. I have a north gable
and a west gable. I could put an exhaust fan in the west gable, which
has a single louvered vent. If I ran it, air would enter through the
vents in the north gable. Most of the attic would be dead air. So
ridge vents will be worthwhile if I get an exhaust fan one day. Before
I bought a fan, I'd install soffit vents.

You might not need the fan. How many cfm would it be? A few large soffit
and gable vents can be as effective as continuous vents, with less labor.

You might keep your attic 100 F on an 80 F day with a 1000 cfm fan, moving
about 1000x20 = 20K Btu/h out of the attic, OR use soffit and gable vents
with area A and an 8' height difference, where 20K = 16.6Asqrt(8)20^1.5,
ie A = 4.8 ft^2, with no fan.

Nick

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