The best location for a yard or garden shed is on flat, level ground, but sometimes a lot does not provide that space. A shed floor still must be level, however, for walls to be properly framed and fastened. That requires special foundation construction, which vary slightly with the slope of the hill. Avoid placing sheds on very steep hills or in areas of heavy water runoff during rains, which might wash away foundations. Locate the shed with the door facing uphill, to simplify construction and provide easier access.
Things You'll Need
- Stake and tall pole
- Builder's twine
- Line level
- Tape measure
- Precast concrete piers or blocks
- Long board
- Beams or railroad ties
- Shed material, wood or metal or vinyl shed kit
- Nails or screws, depending on shed type
- Hammer or screw gun, depending on shed type
Find the slope of the hill with a stake at the top, a tall pole at the bottom and builder's twine stretched between them. Level the string with a line level. Measure with a tape measure the height from the ground to the string on the pole and the distance from the front to the back of the shed area. Base the foundation on these figures; if the back is 10 inches higher, for instance, the rear of the foundation must be 10 inches taller than the front.
Create a foundation with precast concrete piers or full concrete blocks for a difference of no more than 16 inches or two blocks high. Buy piers with metal supports installed if possible; otherwise plan to lay beams on top of the piers or blocks. Set nine blocks in place, one at each corner, one in the middle of each side and three down the center of the shed area. Measure corner to corner and adjust blocks until those diagonals are the same and the foundation is square.
Lay a long board across the side piers and use a level to get it level. Adjust the center piers to fit; remove dirt or add smaller blocks as necessary to get the center blocks to the level height. Check the level across the width and across the diagonals, from corner to corner, and make adjustments until the foundation piers are level in all directions.
Set 4-by-4-inch or 6-by-6-inch beams or supports like railroad ties on top of the piers. Fasten beams to metal supports if using that style; lay ties on top of the piers or blocks. Double check the level once the beams are in place and adjust foundation elements as required or put wooden shims under ties or beams to get the tops level.
Build a wooden floor of 2-by-4-inch lumber and plywood for a wooden shed or assemble the floor elements of a metal or vinyl shed, based on the manufacturer's directions. Set any type of floor frame on the foundation and use a long board and a long level to get it level, in all directions. Adjust the foundation elements or use shims under the floor frame to get the floor level.
Make wooden walls for a wood shed or put together wall sections of a metal or vinyl shed; these techniques will vary with the type of shed. Follow the assembly directions for metal or vinyl sheds. Erect the walls and fasten them to the foundation beams with nails or screws and a hammer or screw gun, depending on the type of material. Install a roof with a shed kit or build one from wood for a wood shed.
- Secrets of Shed Building: Building a Shed on Unlevel Ground
- Fine Homebuilding: A Firm Foundation for a Backyard Shed
- Popular Mechancis: How to Build a Storage Shed
- Boston Globe: Building a Foundation for a Backyard Shed
- Country Plans: An Easy to Build Post and Pier Foundation
- Concrete Piers: Concrete Piers