Shelving units come in handy as clutter builds up in places like the garage, attic or a storage room. Having a consistent plan for building shelving units will make it easy to build a several units at a time. A shelving unit is not complicated to build and should not take more than an hour or so to complete. Construction lumber, glue and a few screws are that's needed to create durable, long-lasting shelves.
Put on your safely glasses. Position the fence so it is 12 inches from the table saw. Position the dado blade so it is 1/2 inch high. Run your 48-inch board perpendicularly across the dado blade, creating a 1 1/2-inch-wide groove that is 1/2-inch deep. Perform two more cuts in the same manner, but for the second cut, position the fence 24 inches away from the saw; for the last cut, set the fence 36 inches away.
Set the 48-inch boards on a work space so they are parallel to each other, 21 inches apart, and with the grooves on the inside. Screw the 24-inch boards perpendicularly to the ends of the 48-inch boards with wood screws so the corners are flush, creating a 24-by-51-inch frame.
Run a bead of glue over the ends of each 22-inch board. Slide each of these boards into a groove of the 48-inch boards.
Position the plywood on the frame, with the corners flush. Screw the plywood to the frame, using the wood screws. This plywood will prevent the shelving unit from swaying back and forth.