Plastic fittings/water pipes and insulating underfloor heating beneath screed?

I just saw the repair by the installer, he used PU foam to align the piping. This might lift the screed for you, PU foam expands as soon as it gets wet. Screed has a certain moisture content, it gets interesting during installation.

Sorry, but what nonsense are you talking about? I'll ask you again: Where are you supposed to lay the cold water pipes?

And PU foam does not expand when water is added in the dried state... by the way, there are different types of foam.

DIN 4140 says Bosy. With heating pipes, I believe it is also 10 cm from the water pipes in an installation shaft (always assuming that they are 100% insulated).

There are fastening guidelines and I probably overlooked the line about PU foam. What do you do if the pipe detaches from the PU foam when pouring the screed? Doesn’t the PU foam even deform the surface of the wastewater pipe? Please never advise users on building a house.

You still owe an answer despite repeated inquiries...

And regarding the PU foam: I see it in the pictures more as an underlay concerning the slope - not as a fastening. As the sole fastening, it wouldn't work for me either...

I don't know the house, so I can't answer your question about the routing of the pipes. I have to guess wall, ceiling, or one floor lower. There could also be another way.