PREPPING GROUND FOR LAYING INDIAN SLATE

[paul01442]

I will be taking some time off work to prep the frontage of my house and would really appreciate any advise. I have got 80 square metres of Indian slate (about 30-50mm thick) that i will more than likely be paying a professional to lay,as i want a good finished job and i dont feel confident enough to do it myself.
I will be hiring a concrete breaker for the existing concrete drive to be broken up and a small 750mm wide mini digger to clear the frontage ,What i need to know is how deep to go down with the digger and what material I.E. hard core,type 1,sub base,(bearing in mind i will be driving cars on it)do i put any plastic sheeting down first, what's the easiest way to level the sub base before using a whacker plate, how much room do i leave for the the slate and the sand/cement.
i would appreciate any info and tips given to me (in simple terms aswell please)
MANY THANKS
PAUL

[thedoctor]

The finshed level needs to be 150mm down from the DPC Paul. If the existing concrete drive was in good condition with no dips or cracks then a sub base may not ne necessary as the existing one was obviously doing its job. If not, then 100mm of scalpings would be required. ( See the project on Garden Makeover to view scalpings) and these must go onto a solid ground base. Any damp spots can be dug out and filled with the concrete you are breaking up. No plastic sheeting is necessary but a weed fabric would be good. This allows water through, but not light, and can be bought from the toolstore. Scalpings can be levelled with the digger blade or a shovel and then compacted to refusal, i.e. they will not go down any more. 50mm of sharp sand and cement to lay the slate, mixed at 8 sand to 1 cement. Keep the mix fairly dry (you should be able to squeeze a lump in your hand so that it stays together but no water squeezes out) and this will give it a little flexibility and its really important its is mixed well, in a mixer. If lumps of sand are allowed to stay "umixed" they will breakdown with water and form voids in the base, the mix around the voids collapses into the void = dip in surface.

[thedoctor]

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