Roof / attic ventilation question

Question

I have read about venting required on 1/300 basis. Is there such thing that roof less than 300 sq ft does not require venting? Would that void manufacturer warranty if 150 sq ft roof without ventilation?

Answer 1

If u put a vent in u will save on cooling in summer.

Make shore u get a vent that can open and close .

A builder i work for has vents in his roof and no aircon and his house is cool.

So it saves money as well

Answer 2

Afraid it doesn't work that way.  1/300 is a ratio, you have 150 sq ft of roof, so -

150 / 300 = 0.5

You need 0.5 sq ft of vent, or 88 sq inches -- 1 sq ft = 144 sq inches, 144 x 0.5 = 88.

150 sq ft, warranty is not that big of an issue, shingle warranties are not fun to deal with anyway, but your roof will be much happier with the vents.