C
Concrete guy
This was one of the fundamental reasons behind the very design and development of Ditra Matting, to allow fast track installation on green screeds.
I understand how these specifications have become belt and braces over the years, particularly since I quit tiling, but we fitted 1000m2's of limestone and marble on concrete screen with UFH over the years and never needed any form of uncoupling membrane on a properly set screed.
The only time we did use Ditra was on green screeds, as back then, that's what it was designed for.
BTW, Azul Valverde (Blue Valley) is a lovely Portuguese stone, very dense for a limestone but it's an absolute pig to grout when flamed. Do consider "pointing" instead of grouting, it will save time in the long run.
