To prepare the ground for a shed, level and compact it. This provides the shed with a solid base that's strong enough to hold foundation materials, the shed itself and the weight of any items stored within.
Before leveling the ground, stake out the area of the shed. Use twine attached to stakes at all four corners of the shed. For sheds on concrete slabs, position the stakes at points that are 1 foot more than the dimensions of the shed bottom to mark the digging area. For gravel bases, position the stakes 2 feet wider than the shed's bottom to allow for a foot of space around the shed for the gravel to extend.
Dig down about 6 inches, as this depth can be leveled out for the shed and is deep enough to support the needed weight. After digging the hole, use a mechanical compactor tamp to compress the soil. While it isn't necessary to make the soil completely level, it should be devoid of any visible dips or rises. The gravel and/or concrete poured on top of the swill provide the level base that the shed needs. Gravel is typically used for temporary sheds resting on sleds or risers, while a gravel layer beneath a concrete one is used for permanent sheds.