I think I've been very stupid

[J Sid]

4mm and 4mm for me

 

[Ajax123]

sorry.. missed this one. decoupling is a must with soft stone over heated screed. british stone federation recomendation.

 

[Sulphurman]

Thanks very much. So I'm looking at about 6mm allowance? Maybe up to 8mm if floor is a bit uneven?

I'd really like your opinions on the way to go over expansion joints in the screed please. I want the stone to just flow through the room space but it's a bit of a funny shape here and there....not sure if I even need any joints.

Will try uploading a plan.

Thanks again for your combined experience.