Hey guys I have a 16x24 shop ive built that needs a roof but im running low on cash, I'm wondering if 2x4 rafters with a 2x6 beam will be strong enough to hold a roof with 4/12 pitch, asphalt shingles, 7/16 osb, and felt paper. I did some calculations lastnight and came up with 4.6 lbs psf. I would be using whitewood(whatever that is) lowes wood no.2 . Also I live in ga so no snow not much wind. Thanks, I can't find much on the net.