Select a general area within the garage for overhead storage. Consider the position of the garage door when open as well as the space requirements for your vehicles and other potentially tall items in the garage when selecting a location.
Slide a stud finder along the ceiling of the garage in the selected area and mark the ceiling joist locations with a pencil.
Select two joists that are 32 inches apart and measure a 48-inch length along them using a tape measure. Mark the end points with a pencil.
Stand the 2-by-4-by-18-inch boards on one 2-by-4-inch end. Align one L-bracket in the center of one 4-inch width at the top end of each board on the 4-by-18-inch side. Fasten the brackets in place using the screws included with them and a screw gun. These are the mounting brackets. The sides that the brackets are mounted on are the inside of the rack.
Place the 2-by-4-by-18-inch boards in pairs on a work surface with the brackets facing each other. The boards should still be standing on end. Space the paired boards 32 inches apart. Place one 2-by-4-by-32-inch board between them for two U-shaped assemblies. The 4-by-32-inch sides should be flat on the work surface.
Drive two evenly spaced deck screws through the outside ends of the 2-by-4-by-18-inch boards into the ends of the 2-by-4-by-32-inch boards using a screw gun.
Raise the assemblies one at a time up to the ceiling and align them with the end marks you made in step three. Drive deck screws through the mounting holes in the brackets into the ceiling joists with a screw gun to fasten the assemblies to the garage ceiling.
Slide the plywood panel over the 4-by-32-inch boards at the bottom of the assemblies. This is the storage surface. You can place lumber, boxes, tools or any number of storage items on the surface.
Repeat steps one through eight to make as many u-racks as needed for your storage system. You may only need one or you may need 12 for your storage needs.