A resin shed is made of plastic material. Resin sheds typically are sold as kits, for a buyer to erect in his yard. They are durable and easy to build. They are light and do not require foundations, but they must be set on a solid base. There are several ways to build a base, but any base must be level, dry and square. Start any base construction by marking corners with stakes and twine and squaring the outline with corner-to-corner measurements using a tape measure. Adjust stakes until the diagonals are the same and the base is square.
Build a concrete base by excavating the area at least 6 inches deep with a shovel. Frame the outline with 2-by-6-inch boards held in place with stakes. Lay 2 inches of medium gravel in the form, compact it solidly with a hand tamper and fill the form with concrete. Level the concrete by dragging a long board across it and finish it with a smoothing trowel. Let it cure for a week before erecting the resin shed.
Use large square concrete blocks to make a base. Dig out the area about 6 inches deep. Cover the ground with a plastic membrane. Spread a layer of compacted gravel over the membrane and top it with about 2 inches of sand. Set square concrete blocks, 2 or 4 inches thick, in the base, with edges touching. Level the blocks with a level; adjust the sand to get blocks even. Sweep sand into the joints between blocks with a broom to secure them.
Make a base with plastic squares. Buy interlocking plastic grid blocks to fit the resin shed base dimensions. Level the ground in the base, cover it with plastic membrane and spread a layer of fine gravel over the membrane. Set the blocks in place, locking them together at joints. Cut blocks with a circular or reciprocal saw as needed to fit.
Fill a base with compacted gravel. Dig out the area 6 to 8 inches deep, smooth and roughly level it with a rake and spread a plastic membrane over it. Lay down gravel, starting with a layer of medium gravel 4 to 6 inches deep. Compact it solidly with a hand tamper. Add 2 inches of fine gravel and compact it firmly. Set the resin shed floor directly on the gravel.