4inch screed or 150ml concrete tile???

[Graeme M]

I have a quarry tile kitchen floor with Bitumen coating.

I am having this taken up so I can flatten the floor, lay a damp proof membrane and finish with some ceramic floor tiles

I had a few quotes from builders, but there are two schools of thought...

1 - dig up what is there and dig out a considerable amount of sand underneath the quarry tiles. Fill with compacted rubble then lay a 4 inch thick layer of screed. Leave to set then lay the ceramic tile

2 - dig up just the bitumen and quarry tiles. Flatten and compact. Lay damp proof membrane and then lay 150ml concrete slabs. Lay a thin layer of coating (not sure what) on top of these slabs and then lay ceramic tiles

Any issues with number 2?
I would imagine if the ground below moves, then could lead to some problems.
We are having a granite worktop put on which would increase the weight - make any difference?

Number 2 is cheaper option by all accounts, but the deciding factor is that the builder who can do it in the timescale I want uses this option.

Opinions appreciated

Thanks

 

[shaggy]

What I would favour would be a variation of your 1. Compacted rubble blinded with sand, dpm, polystyrene insulation, 4"concrete, 2"screed.
Alternative would be to put the polystyrene on top of the concrete and moisture resistant chipboard instead of the screed.
It's more work but it's a proper floor. I don't think timescale should be the priority because a skimped job may give problems later.

 

[masona]

Just to add on,

You could also put exterior plywood screw down on top of the chipbroad for the floor tiles.