Does the Arrow Select shed include a floor, and what should it stand on?

No. The box is panels, door components, the internal frame and hardware; the floor is yours to provide. Build the shed on a flat, solid and level base — a concrete pad, patio blocks or a compacted gravel pad all work, and a level base matters more than the material because the walls have to stay square while you assemble them.

Arrow also makes steel base kits that frame the shed and hold it off the ground, with the floor of your choice laid inside. Each kit lists the shed sizes it is made for, so check that list against your shed before ordering one — not every Arrow shed size has a matching kit.