I suppose that being in the South may have something to do with this but my county doesn't consider a "Garage" to be indoor space. Actually the only consideration for a permit was the square footage of the building, the permit was accessed at $0.25 per foot. Even if I add HVAC it's still not listed as "Heated" space.
The main reason was using PT over common was purely cost. A 2"x4"x12' was $15.38 for common and $9.99 for PT.
Still looking into the nail gun.