my plan for my 20x30 single story calls for 3 2x10s with 1/2" plywood laminated built up beam.
if i am going to put a loft on 1 side do i need to make my beam a 2x12 built up beam?
my side walls will be 10'
That would be a good idea. The beam depth is the difference between the 1 story and the 1-1/2 story design (the pier spacing is the same).