You might want to watch some YouTube videos, from Great Western Buildings and Eric Beavers. 

He says his buildings and company were designed mostly for the DIY customers.


Has some good videos, about erection to watch.
 

Some items, I don't get, is he says he always put a grit at 7"6"' ( Why not closer to 8 foot, if you wanted to line the lower interior walls with 4x8 sheets of plywood ???)

One video, he mentioned, they do offer "Flush grits and/or purlins" also, verses the typical "By-pass" grit and purlin system. (note: looks to me that the by-pass system wastes interior space) My Dad's old 1977 Butler Farmstead building is Flush Grits and Purlins design. Even this Butler Main frame, sticks out somewhat and you have to be careful with tall forage wagons, and wide tall gravity boxes = Heck, bypass grits would even be worse, with main frame being set "inside the interior footprint", even more. 

I've read, by-pass style is cheaper and they get by with less steel.