chris French presented the following explanation :
Note that the joists on sheds aren't that thick and need plenty of support as
well, each corner won't do.

Indeed.... I home built a heavy timber 14' x 14' summerhouse last year
and used 3x2 joists for the floor. I spaced the supports at no more
than roughly 24" apart throughout the base.

All I did was level the area no more than was needed, then dug down to
lay in the support piers where required. I removed any soil which had
been disturbed, so the supports sat on undisturbed soil in the bottom
of the holes. This was to ensure even settlement. I also made sure
there was a good three inches clearance at the lowest point between any
timber and the ground.


No there is no need to cover the ground with anything. Nothing is going to
grow it's to dark

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I certainly didn't worry about removing any grass and what there was,
quickly died off.

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Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.org