For the purposes of this chapter, public warehouses are classified as follows:
   (1)   Class 1 warehouses have less than 10,000 square feet of floor space.
   (2)   Class 2 warehouses have 10,000 square feet or over but less than 50,000.
   (3)   Class 3 warehouses have 50,000 square feet or over but less than 100,000.
   (4)   Class 4 warehouses have 100,000 square feet or over but less than 150,000.
   (5)   Class 5 warehouses have 150,000 square feet or over.