Cut out Klx110 when wet

Murexin DB80 as a fill under the screed

I don't know the Murexin product, but my cement-bound fill has certainly not noticeably followed, otherwise my door frames would now fly off.
Do you need a bulk thickness of 30 cm? That's pretty tough, I only have 9 cm and there are even 75 ventilation hoses in it. If there is only one thick obstacle in the one room where you need 30 cm, I would make the fill normal thick and later put XPS on top of that one obstacle. Otherwise the 30 cm won't dry you forever and I would also have concerns about the stability.
The joints in the cement screed were pretty much made when I was wet. The site manager said they were already pegged, so I assume they put something in there from the start.

1retro wrote: My screed layer thinks that he will do it with a "Flex" after a drying time of approx. 4 to 5 weeks ...

THAT I would be very surprised, because you do the trowel cuts exactly for the reason that you tell the screed where to make its drying / shrinkage cracks ...

In terms of fbh, I imagine the subsequent flexing is also not uncritical, belongs bsplw to every outside corner ... Good Morning,

With us, the filling was also made with the Murexin DB80 and could not complain to this day, but at 30cm I would consider whether I should not only let the filling up until all the pipes are covered and then with EPS / XPS at the desired height go Would have the advantages that it is probably cheaper because it is self-made, better U-value and more pressure-resistant.

To the Flex-Gschichtl .... you better look for another screed layer;)

Ps: Floating screed has no separating joints at all, which is a great advantage later when laying the floor.
Kind regards