How much depth to leave for top soil and turf?

[datadiyer]

Hi All,

I have about a foot and a half depth of area in my garden which needs to be turfed. I also have a lot of rubble left over from my garden project which i'd ideally like to use. Any ideas on how deep I can get away with filling with rubble before I have to put top soil and turf down? Also, is this the was to go? I was thinking a bit of rubble can only help with drainage?
Many thanks,
Datadiyer.

 

[r896neo]

You need a good six inches at the very least. But if you want it to grow well and thrive i would go for a minimum of 8''