A Tricky One A Second Opinion Required

[Rossymcg]

Got a kitchen/

dining room to do with a loveley red/white/green/pink marble, it 4 meters wide and 7 meters long with eufh. Simple so far.
However one part of the floor the 1st 3.5 meters in length is a suspended concrete floor, rock solid no deflection, 2nd half suspended timber floor also solid no deflection,
Concrete floor has black vinel tile adhesive residue, suspended timber floor has been re laid almost perfectly level with insulation under 18mm marine ply, nogged out, ply is clean as it was left off till after plasterer had been, and ply sits 25mm higher than concrete floor,(concrete floor runs out of level by 25mm and I intend using 20mm insulated backer board and SLC the 5mm back too level,
So how would you go about it?
Slurry the black adhesive or scrape it off?
Put a soft expansion joint at the point of the two different substrates,
1 ufh mat or 2? 1 over each substrate? I won't be putting any insulated backer boards over ply as 100mm kingspan sits below ply, would you put a slip mat between the ply and stone?
Ufh will be 150w I don't think I need to decouple that from the marble tiles, what do you guys think?
Cheers

 

[Old Mod]

Remove as much 'black' as u can, and use TM's prime+grip on floor.
Expansion between two substrates.
Insulation boards glued and screwed with Wedi washers.
Latex concrete to level.
Two substrates, two UFH mats, two controllers.
SLC over mats, and decouple each side individually.
Always decouple stone from heating.
Set floor with joint along expansion joint in substrate.
And soft joint between two floors if they won't have proper expansion joint.

 

[Rossymcg]

Pretty much how I was going to do it, it's a twitchy one, a beautiful stone but soft and lots of veins,
Anyone ever used mapei mastic for all joints instead of grout? I've seen something like this done in poland

 

[hmtiling]

It will be fine as long as 2 floors treated separately and expansion joint used. Remember to let the joint carry through the decoupling.
I've siliconed many a joint on a tiled bath panel and had to tile a timber staircase which i siliconed every joint but you won't need to do that here. Good luck!

 

[hmtiling]

If they won't go for a proper expansion joint you might want to consider this stuff as it will give more protection to the edge of soft stone than silicone
Micro joints - Coloured Movement Joints

 

[Stu Lilley]

Got a kitchen/

dining room to do with a loveley red/white/green/pink marble, it 4 meters wide and 7 meters long with eufh. Simple so far.
However one part of the floor the 1st 3.5 meters in length is a suspended concrete floor, rock solid no deflection, 2nd half suspended timber floor also solid no deflection,
Concrete floor has black vinel tile adhesive residue, suspended timber floor has been re laid almost perfectly level with insulation under 18mm marine ply, nogged out, ply is clean as it was left off till after plasterer had been, and ply sits 25mm higher than concrete floor,(concrete floor runs out of level by 25mm and I intend using 20mm insulated backer board and SLC the 5mm back too level,
So how would you go about it?
Slurry the black adhesive or scrape it off?
Put a soft expansion joint at the point of the two different substrates,
1 ufh mat or 2? 1 over each substrate? I won't be putting any insulated backer boards over ply as 100mm kingspan sits below ply, would you put a slip mat between the ply and stone?
Ufh will be 150w I don't think I need to decouple that from the marble tiles, what do you guys think?
Cheers

3_fall got it spot on ... The only diff I would do is Mapei Eco prim grip with utraplan renovation and ditra heat tb to heat and uncouple. Always use expansion with change of substrate