I’m considering some large format porcelain tiles to lay externally. We have a cement slab outside, but it needs to be built up by about 90mm before we lay the porcelain tiles. What build up should I use:
flow screed?
sand and cement screed?
something else?
ditra matting?
Do I need to make sure the build up is dry/cured before the porcelain goes down or does it not matter for external purposes?