1200 SF light commercial space with 2ft tall flat trusses with plywood deck and new PVC membrane roof. Fitting out for "gallery" and trying to maintain the industrial look of the open truss ceiling as the bottom rail is 9ft above floor. Thinking about spray foam to underside of deck but uncertain of best RValue and how to keep the trusses looking right if the entire upper 2x6 rail is obscured by foam and how to finish the surface of foam to make aesthetically pleasing. Have thought about T&G between the trusses and even cladding the trusses. Any suggestions or ideas, we are open to using batt insulation because of reduced cost but then not sure how to keep the look we are trying to preserve.