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?

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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