Laying tiles on floors with radiant heating

There are three phases to this tiling work: making the mortar filling, laying and grouting the tiles and making the dilatation joints. On flooring with radiant heating, the dilatation-contraction movements need to be counterbalanced technically with a good elastic joint.

1st step: adjusted pipe-cover filling:  
--- 1st Option: more labour-intensive but less expensive. Recrecem Pre-Mix
--- 2nd Option: with self-levelling mortar: less labour-intensive but more expensive Fix-Nivel
2nd step: ultra-flexible laying of stone or ceramic tiles on mortar substrates with good planimetry Tecnoflex / Tecnoflex Thick Layer
SEALING (recommended) Eurocolor Flex
EXPANSION JOINTS (obligatory) Sellalastic