Hi,
I'm getting a ten by eight (or maybe a bit bigger) shed, and need to build a decent surface for it. The site is slightly sloping. It will be a fairly good quality shed, so I don't want to skimp on the foundation too much.

Casting a whole slab seems like overkill, so I was thinking of running three strip foundations the full ten foot. They'd be 100mm deep, if not 200 (might need to be 200 to get it remotely level!). I'd then put the shed base on 3" fence posts, sandwiched between roofing felt layers to stop transfer of damp.

So, the questions:

1) how wide should the strips be - a foot?
2) is 100mm deep enough?
3) should I just cast a slab instead?

Thinking about it, it would probably have to be 200mm, with a small layer of packed hard core in the base, to level up.

Thanks,
Nathan