i'm planning on replacing my kitchen floor, its 4" concrete and badly cracked and uneven on investigating i've found there is no hardcore under the excisting just earth.I'm planning on digging out the existing and replacing the area is 16m2 my plan is to lay and compact hardcore base then builders sand to allow for dpm then lay a 4"base, does this sound about right? i would be grateful of any hints or tips also what concrete mix do i need i was thinking 5:1 thanks.geez.