If you are like most people and would like some additional storage space, consider building your own storage shed. A 12x12 storage shed is fairly easy to build and will ease some of that overcrowding in the garage. Follow these easy steps to do it yourself.
Choose a flat area of your yard for the shed and level it with a pick and shovel. Compact the soil with a hand tamper or plate compactor to prevent any settling.
Place the five 4x6 pressure-treated beams on the ground, spaced 36 inches apart on centre and parallel with one another. Check that the beams are all lying level with a carpenter's level. Make adjustments to the ground underneath the beams as needed.
Build the floor frame. Use two pieces of 2x4x8 lumber for rim joists. Make floor joists by cutting 2x4x12 lumber to a length of 141 inches. Lay the floor joists 16 inches apart on centre and parallel to one another. Lay the rim joists perpendicular to the floor joists, serving as end pieces. Nail the floor joists to the rim joists. Cover the floor frame with 5/8 inch, 4x8 plywood sheets cut to size so that the edges of the sheets are flush with the frame and nail it. This will be the floor decking.
Use 2x4x12s as top and bottom plates for your walls. Use 2x4x8 lumber as the studs for the walls. Nail the studs to the top and bottom plates every 16 inches on centre. Frame out openings for your planned doors and windows in the wall. Repeat this step for all the walls.
Raise the wall into place on the floor decking. The outside edge of the bottom plate should be flush with the outside edge of the floor decking. Screw the bottom plate to the floor using the heavy-duty 3-inch screws. Repeat for all the walls. Make sure all the walls are plumb and square and nail them together.
Nail another set of 2x4x12 top plates directly on top of the existing ones on the tops of the walls. Make a mark on the top plates every 24 inches on centre. You will use these marks as locations to set the roof trusses.
Raise and nail one of the end trusses flush with the outside edge of the top plates. Raise and nail the other trusses to the top plates, using the marks to ensure they are 24 inches apart on centre. Deck the roof by covering the trusses with sheets of 5/8-inch plywood in the same way you did the floor decking.
Cover the plywood with asphalt paper, tacked down to the plywood with roofing tacks. Install a drip edge. Shingle the roof.
Cover the outside walls with 5/8-inch channel siding or an exterior siding of your choosing. Nail it, leaving a 1-inch overhang on the bottom. Trim and paint.
Roof trusses of this size can be put under considerable stress and loading. Pre-order engineered roof trusses from professionals.