On Apr 9, 11:29*pm, Home Guy wrote:
gonjah wrote:
Should I still be using my attic fan during still periods?
I thought they were not cost effective.

I try to not have my attic temperature exceed 100 degrees F.

100F isn't much in temperature for an attic. Consider that
the attic should already have the thickest insulation in the
house. Maintaining 75F inside with the attic at 100F is
only a temp delta of 25F. Would you be similarly concerned
when the outside temp was 50F during heating season and
the walls, which have less insulation are all exposed?
Of course not, because the temp delta is small enough.






So I'll turn on my attic fan when-ever the temp hits 100, wind or no
wind.

I have a 1500 sf house. How many sf should I have in

soffit vents?

You should have a soffit vent hole between every rafter joist.


Take a look at the post by HeyBub where he goes through the
calcualtion. His target of 1 sqft of vent for every 150 sqft of
attic I've seen used before and seems reasonable.

I'd prefer a continous soffit vent, rather than individual ones.




If you have aluminum soffit, there's no excuse for not having perforated
aluminum soffit along the entire length of the eves. *If you have mostly
(or totally) solid aluminum soffit, take it all down and replace with
100% perforated soffit:

http://www.biytoday.com/Soffit2.jpg

Just cut a hole the size of your hand with a jig saw in the existing
plywood soffit every 16" before you install the perforated soffit.

And remember that anything you do to improve soffit ventilation is
wasted if you have attic insulation jammed into the eves blocking air
flow.