I’ve read you need 1sqft vent for every 300 sq ft of attic space. To get that figure, do I just look at ceiling measurements, nice and square, or do I gotta incorporate triangle math for a the cubic volume?

I’m redoing my roof soon and thinking about changing the venting. Currently has about 4 flashed vents per peak and intake under the eaves.

I want to do a vented ridge, but there’s a 2x6 running under the peak. can I rip 1.5 or so inches of the sheathing on both sides and get a running 1/2 gap on each side to do the trick?

Also looking at gable vents. Any reason to lean one way or the other?

Thanks y’all!

I’ve done a lot of construction and roof adjacent work but never fully done this one my own.