Tiling a room with multiple sub floors

[Alphadock]

http://www.marmox.co.uk/products/marmox-waterproof-insulation-board

Second paragraph..........

 

[White Room]

I'm staggered at that statement from Marmox, they state it on their site so fair play but my brain has just gone onto overload, read their site before and must of missed that.

Just to add, I bet schluter would have something to say about it.

 

[Spare Tool]

Sure i actually mentioned somewhere in this thread that insulation boards do infact help to uncouple a floor, but imho it is no substitute for a dedicated uncoupling membrane...ditra heat matt is a totaly different make up to standard ditra and i stand by the technical fact sheet i have that states the ufh wires must not touch the top of the standard ditra....
I did however email schluter for my piece of mind and they stated that expansion joints 'must' be fitted at the exact point where the different substrates meet, so hold my hands up n say i was wrong on that point, but this kitchen floors gonna look a right dogs dinner with expansion joints cut skew wiff all over the place, sometimes you just simply cannot do everything to the rule book

 

[Alphadock]

On the subject of not doing things "by the book", I had this same 'timber meets screed' situation at my in-laws.
Instead of putting an expansion joint where the two substrates met, I had a tile span the joint and bedded the screed side with adhesive as normal and spot bed the timber side of the tile with silicone.
Now this may be bad practice but there's no arguing when 8 years later the floor is still perfect.
They were just a ceramic tile and no ufh though.

Back to the original post, how do you mean "schluter might have something to say about it"?

And
If marmox say their product is an uncoupler (dedicated? Or not)who are we to argue, surely they've researched and tested this claim a lot more than any of us!

 

[peterparker]

Well Mapei disagree with you (and Schluter). Schluter say you should NOT use a modified adhesive because it needs air to 'cure' but none can get through the tile or ditra.

I had a long chat with Mapei technical department and they were adamant that this was nonsense and Keraquick + latex liquid was what they would recommend for 90 x 90 tiles and these circumstances.

Confusing to say the least!!