Posted: 15/10/2014 at 13:50
Why are you against the idea of a concrete base, can I ask?
We had some old concrete paving slabs that were going to be chucked out anyway, so we arranged these on levelled, compacted sand and mortared them in. Same sort of thing. We then stuck our shed on blocks, so it wouldn't be in direct contact with concrete. Has helped too reserve the floor if shed from rotting in the wet.