Step 1
Measure the length and width of the shed along the lower edges of the shed. Cut two 2-inch-by-6-inch wood beams to the length measurement with a circular saw and two additional beams to the width measurement minus 3 inches.
Step 2
Assemble the four beams into a basic box shape with the ends of the width beams sitting against the inside edges of the length beams. All 6-inch sides must stand vertical. Drive two 3-inch, self-tapping, exterior-grade wood screws through the length beams into each end of the width beams with a drill and screwdriver drill bit creating a basic box.
Step 3
Measure and place vertical marks on the inside edge of each length beam every 16 inches from one end resulting in a pair of marks. The last pair may be closer than 16 inches to the end.
Step 4
Cut additional 2-inch-by-6-inch wood beams to the width measurement minus 3 inches. Attach the beams with wood screws to the box frame so that one beam is placed centered on each pair of marks creating the subframe for the floor.
Step 5
Attach plywood sheets to the top of the wood frame with 3-inch wood screws spaced every eight inches along the vertical and horizontal beams. Cut excess plywood off flush with the exterior edge of the frame using a circular saw.
Step 6
Attach the Arrow metal shed to the floor with 3-inch wood screws drilled through the base supports of the shed into the floor, or using an anchor kit available direct from Arrow.