Roof questions

[rennyboy]

I have had several estimates on tearing off 2 layers of shingles and installing new shingles, they all have been at around the same price ($6K), but my the last guy told me that adding ridge vents and keeping the attic fan are counter productive, he is the only guy to say this, is he right? I also have soffit vents. Should I install a new attic fan and forget the ridge vents or vice versa? I want to keep the attic as cool as possible.Thanks in advance

[HayZee518]

ok, soffit vents are ok but remember heat rises. the soffits are at the bottom of your rafters. the rising air tends to draw cooler air up into the attic. once the cooler air goes up, without ridge vents it just hangs there getting heated.

[Hube]

Soffit vents only are no good at all without high (near the ridge) vents. Ridge vents are the BEST. Soffet and ridge vents allow air to come IN and go OUT.
This air movement will allow roof shingles to last longer,and lower attic temperatures.
Make sure you have enough vent area; For every 150 sq ft of attic floor area there should be at least 1 sq ft of free vent area, divided 50/50 between the soffit and ridge vents.
NOTE:
As long as there is adequate insulation in the attic floor, you can never have too much ventilation in an attic.....and always make sure that the soffit vents are not being blocked by any insulation.

[rennyboy]

thanks for the info hube, so you are saying to add the ridge vents and keep the attic fan also, correct?

[Hube]

If you have proper air coming IN from the soffits and proper air going OUT at the ridge, then that is all that is necessary.
A fan is normally not required IF soffit and ridge vents are sized properly
For each 150 sq ft of attic floor area; 1 sq ft of "free" vent area.
1 sq ft = 144 sq in.
Example; a 12 x 12 opening has an area of 144 sq in ( 1 sq ft)....but if this 12 x 12 opening is screened with a 1/4" mesh, then the "free" area is cut down approx 20% to only 116 sq in.
Example; An attic floor area of 900 sq ft would require a MINIMUM of 6 sq ft of "free" vent area
(divided 50/50 between soffit and ridge)
Thus 3 sq ft of "free vent area would be the MINIMUM amount required for the soffit and also the ridge.
Make sure you have enough area, and keep in mind as long as you have good insulation within the attic you can never have too much venting.