Notwithstanding any other section of the state building code, chapter 19.27 RCW, or any other code adopted by reference in chapter 19.27 RCW, approved portable oil-fueled heaters may be offered for sale, sold, and used as a supplemental heat source in structures in the state. Portable oil-fueled heaters which are not approved may not be offered for sale, sold, or used in this state. Any approved portable oil-fueled heater may be offered for sale, sold, and used in locations other than structures unless specifically prohibited by laws of this state.