Wis. Stat. § 99.015: Warehouses classified.

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.