We are doing a building on pilings and have decided we want to spray urethane insulation on the underside of the steel pan deck and then apply a polyurethane coating. This is on the exterior of the building under the floor slab raised up on concrete pilings. Are there any Smoke Development or Flame Spread requirements for an exterior application like this? This is not a crawl space, but rather open to the environment, but at one end the floor does butt into the hill side at grade so the clear area under the elevated slab goes from several feet to zero. I can find no code application for an unenclosed floor.