Arrow sheds offer a myriad of accessories, including a metal frame to be used with plywood as a floor and base for the company's line of sheds. The company offers basic instructions for building your own wood or cement base if desired. Building a concrete foundation for an Arrow 10-foot-by-8-foot shed takes a few days and can be accomplished prior to building the shed. Anchoring the shed to the foundation should be done after the concrete has cured for two to three weeks.
Mark the ground with the perimeter dimensions for the shed plus 3 to 4 inches.
Dig out the area for the concrete pad to a depth of 6 inches. Compact the ground with a hand tamper, which is a long pole with a flat, heavy base and two handles on the side, or a mechanical tamper available for rent from most hardware stores.
Place landscape fabric over the base of the hole. Overlap the sides of the hole slightly and any seams in the fabric by 3 inches.
Place 2-inch-by-6-inch boards along the edges of the holes. Cut two boards 8 feet 3 inches long for the sides of the hole. Stand all boards so that the 6-inch side is vertical. Hammer 3-inch nails through the sides of the 8-foot-3-inch boards into the ends of the 10-foot boards to create a rectangular form measuring 10 feet by 8 feet along the inside edges.
Place the form in the hole. Drive stakes into the ground with a mallet every 2 feet along the exterior edge of the form. The tops of the stakes must sit flush with or just below the top edge of the form.
Place a level on top of the form. Raise and lower the form until the structure is level side to side and front to back. Anchor the form to the stakes with 3-inch nails driven through the stakes into the form once the form is levelled.
Pour a 1-inch layer of crushed gravel into the hole. Compact the gravel with the tamper. The gravel's surface should be 5 inches below the top of the form. Add or remove gravel to achieve the proper depth.
Mix and pour concrete into the hole until the hole is half full. Lay strips of rebar on top of the concrete into a grid of 2-foot squares.
Fill the remainder of the form with concrete until the concrete is flush with the top of the form. Drag a spare board along the top edge of the form to remove excess concrete and to level the concrete surface.
Pull a float across the top of the concrete to smooth the surface. Allow the surface water to evaporate and leave a dull-grey appearance to the concrete.
Finish the concrete surface by smoothing it with a trowel or dragging the bristles of a push-broom over the surface for a skid-resistant finish.
Allow the concrete to cure while covered with plastic for seven days before applying sealant or paint, and wait two to three weeks before attaching the shed.