Sustainable farms need sustainable buildings—and a CALS professor provides an option
By Bob Mitchell BS’76
Lofty red barns may be Wisconsin icons, but the real workhorse structure in agriculture today is the post-frame building. You can’t drive very far down a rural road without spotting one being used to house livestock, store and repair equipment, shelter hay or myriad other uses. Virtually every new structure on a modern farm gets built this way, and with good reason. Post-frame buildings are versatile, easy to assemble and affordable.
And now they’re becoming more sustainable, thanks to a “Green Frame” building system being developed by Dave Bohnhoff, a CALS professor of biological systems engineering.
Unlike traditional post-frame construction, Bohnhoff’s system isn’t based on preservative-treated wooden posts embedded into the ground. He uses non-treated wooden “I-posts” affixed to precast concrete piers. The I-posts are sandwiches of dimension lumber and laminated-strand lumber that are structurally and thermally more efficient than timber posts. Another sustainability feature relates to how the frame parts go together. The frame members that tie and brace the vertical posts and roof trusses have reinforced, deep notches at the ends that mate with adjoining pieces. This makes assembly easier, safer and more accurate. It also makes it easy to disassemble and reuse the components when a building outlives its usefulness as the farm enterprise grows and evolves.
Will all of those non-standard parts drive up the cost? Not at all, says Bohnhoff. The beams, connecting pieces and concrete piers can be fabricated on site using materials available in most lumberyards, tools found in any farm shop and basic construction skills.