So I am contemplating a new lawn instead of the loose stone that is there. Currently it has like I said loose stone over a membrane and then obviously soil, which is more than likely clay soil. I have been thinking about how to do it and my idea is to remove stone temporarily, take of membrane, turn over soil and level get new membrane, put loose stone back on and then get some new top soil, level and finally put turf on, my only hesitation is would an inch of topsoil above the loose stone work for the turf or would I need more?.