Building a Lean-to Shed
A small shed like this has an advantage over a large garage: It’s not big enough to become a hopeless mess with tools buried out of sight. You can build a larger structure, but make it longer, and not much wider, so that it will be easy to keep organized. If you do make it wider by a foot or more, use 2x6s instead of 2x4s for the rafters and the floor joists.
Plan the size according to your needs. You may want to install a workbench or a potting bench. Be sure all your tools can be hung within easy reach, so you don’t have to pile them up in a corner. If you want to do some carpentry work out of the shed, plan to store sawhorses in it, so you can quickly bring them outside. You may want to have an electrician install a receptacle.
If you live in an area with severe winters, frost heave will cause shallow footings to rise and fall, perhaps as much as an inch. If your shed will be attached to the house, it is important that it not rise and fall while the house stays still. So either leave it unattached, or check with local regulations, and be sure to dig and pour footings that extend below your frostline—the depth to which your ground freezes during the winter. Because the structure will be exposed to the weather, use pressure-treated lumber and plywood throughout.
Tools: Circular saw, posthole digger, drill, hammer, tin snips, level, tape measure.
1. Install footings. Mark the outline of your shed with stakes and string lines, and check for square. Because the footing of a house is usually wider than its walls, you will probably not be able to dig right next to the house. Dig post holes at least 24 inches deep, or below your frostline. Shovel a few inches of gravel into each hole. All the footings must be level with each other. Use a level and a straight board to find the highest spot, and start there. Insert a tube form and anchor it as shown. Then anchor all the other tube forms at the same level.
2. Build the floor. Cut two 2x4 headers to the exact length of the shed, and cut the joists to its width, minus 3 inches. Work on a large, flat surface. Lay the headers side by side and mark them for joists every 16 inches. Set all the pieces in place, and attach with two 3-inch deck screws at each joint. Set the floor frame on the concrete footings, and check for square. Cut pieces of 3/4-inch pressure-treated plywood to fit. Attach the plywood to the joists with 1 5/8 inch deck screws.
3. Frame the shed. Attach a ledger board to the house, 8 feet above the floor. Make sure it is level, and that its ends are plumb with the ends of the floor. Build the 7-foot-high front wall by laying it out on the floor. Raise it into position and temporarily brace it so it is plumb. To make the first rafter, have a helper hold a 2x4 in place while you mark it. Use it as a template for the others. Attach the rafters with angle-driven 2-inch decking screws. For the side walls, measure each stud individually, by holding it in place with a level to make sure it is plumb while you mark it.
4. Build the roof. Cut 1/2-inch plywood to fit, so it overhangs the rafters by 2 inches on all three sides. Attach with 1 5/8 inch deck screws. Staple on roofing felt, and lay the shingles. Where the roof meets the house, install flashing; consult with your supplier or inspector for the right installation on your house.
5. Attach siding and trim. Cover the exterior of the shed with siding. Make it snug against the house, and keep it about 2 inches above the ground. Caulk the joint where the plywood meets the house, and trim the outside corners with pieces of 1x3 and 1x4 lumber.
6. Add window and door, paint. Make the door out of a piece of sheet siding, or use 1x6s with no spaces between them. Attach to the shed with T-hinges; add a door spring if you want it to close automatically. Add a gate latch, or install a hasp with a padlock for security. Install your window, and trim it with butt-jointed 1x3s. Apply two heavy coats of exterior paint to the siding, taking care that the bottom of each piece of lumber gets plenty of coverage.