I am looking to self build a large shed this year, but lack of access will make laying a solid concrete plinth quite difficult and probably expensive. My alternative solution is to dig suitable holes at the corners/middle, pour concrete, then use either concrete lintels or sleepers to span the pads and support the floor joists of the shed. The shed is going to be more substantial than the usual bought variety. Using 3x2 stud walls, 6x2 floor joists and 4x2 roof joists. Clad in feather edge board, insulated throughout. Any recommendations on the foundations? Depth and cross section? Should I reinforce?