Yes, directly to the underside of metal roofing and walls. Eliminates condensation (huge issue in Ohio winters) and amplifies usable square footage. Closed-cell only; never open-cell on a pole barn.
More detail
Pole barn foaming is increasingly common across Greater Cincinnati exurbs (Liberty Township, Mason, Goshen) where homeowners convert pole barns from cold-storage buildings to year-round-usable workshops or recreation spaces. The two issues that pole barns face: (1) condensation on the underside of metal roofing every cold morning, dripping water onto stored items and corroding the metal from the inside; (2) extreme temperature swings (130°F summer, 10°F winter interior) that limit usefulness. Closed-cell foam sprayed directly to the underside of the roof and the inside face of the wall sheeting solves both: no air movement through the metal so no condensation, and R-21+ insulation that lets a small heater or mini-split keep the space comfortable year-round. Closed-cell only because open-cell is vapor-permeable and would let moisture migrate to the cold metal surface, corroding it from the back. Cost $5,000-$15,000 for typical 30x40 to 40x60 pole barns. Cincinnati pole-barn-conversion sequencing: most homeowners foam first to stop condensation and stabilize the interior temperature, then add a heating source (mini-split, propane heater, wood stove) once the foam is in place. Adding heat before foam wastes meaningful fuel and can drive additional condensation under the metal roof. Sequence the project foam-first.