I just bought a small ranch here in southern Arizona not far from Tombstone. Near the house is a 30'x30' concrete slab 12" thick in beautiful shape with j-bolts already set in. I want to build a barn/garage combination building on this slab. Here is my quandry:
I'm planning to construct the walls from 2x6 studs 24"o.c. sitting on a 2x8 PTL plate. I would like to keep the ground level and "loft" areas as open as possible. I've been working the numbers for a while trying to find the best way to cover a 30' span. So far I've come up with two possibilities: 1) Bridge the span with wood I-beams. My calculations indicate that I will need 18" I-beams/joists 12"o.c. to do the job (very expensive!). 2) Bridge the span with 2x12 joists of grade 2 (or better) lumber 24" o.c. and support them halfway with a beam made from five layers of 2x12s, which is itself supported by a lally column. The first option gives me the open area I want, but will cost a small fortune. The second option is cheaper, but will leave a steel column right in the middle of the ground level. Is there another option that I've missed? Considering strength and economy with my desire to create an open ground level, how would you approach this challenge? Or, am I just completely off base with my engineering?