For truck trailers, one space for a gross floor area of 5,000 to 20,000 square feet; two spaces for gross floor areas of 20,000 to 40,000 square feet; three spaces for gross floor areas of 40,000 to 70,000 square feet; four spaces for gross floor areas of 70,000 to 100,000 square feet; and for each additional 50,000 square feet or a fraction thereof, an additional space is required.