Cellar floor

[Antony higo]

I'm laying a new concreted cellar floor. I'll be getting a local builder to do the concreting bit but I'm wanting to do most of the prep. work myself to save some money. I'll be digging it out, putting down hardcore/sand and a membrane. My questions are. How deep do I have to dig (was thinking about 8 inches). How many inches of hardcore. How many inches of sand. And where do I put the membrane (under hardcore, under sand or on top of sand)? I'm pretty clueless about this sort of thing so any help would be much appreciated. Something else I've seen is you can put insulation down under the concrete. It's not something I'm considering but out of curiosity is it just normal kingspan insulation board you use. Surely this would just crack under the weight of concrete (or soak it up). Thanks in advance for any help you can give me.