DIY: Shed Supports

Measure the outline for the shed foundation with a tape measure. Drive stakes into the ground, with a mallet, at the corners of the outline. Then tie strings to the stakes to mark the edges of the foundation.

Remove the topsoil over the foundation outline down to a uniform depth of 4 inches, with a shovel.

Fill the foundation bed with crushed rock, gravel or sand. Level the medium with a rake and builder’s level.

Measure 2 feet from each corner along the perimeter of the outline. Drive stakes into the ground at the 2-foot marks, with the mallet. Tie strings to the interior stakes, running the strings between opposing stakes, both lengthwise and width-wise across the foundation bed.

Place a precast concrete footing at each of the four spots where the interior strings intersect. Orient the footings with the beam channel in the footing facing upwards and parallel to the interior strings running lengthwise along the foundation. If the shed is square, run the footings channels in the opposite direction as the roof joists.

Place additional concrete footings every 3 feet, centering the footing under the interior strings running lengthwise along the foundation. Run 4-by-4-inch foundation beams through the footing channels. Drill pilot holes through the beams and into the footings with a 1/4-inch concrete drill bit. Attach the beams to the footing with 1/2-inch diameter concrete bolts -- two inches longer than the thickness of the beams -- and a socket wrench.

Set the shed floor on top of the foundation, and secure the floor to the beams with wood screws and a screwdriver. If you are constructing the shed from scratch, lay the floor joists perpendicularly across the beams. Toenail the floor joists to the foundation beams with number 10 nails and a hammer. Space the nails every 16 inches, alternating the nails on opposite sides of the joists.