Is an 8cm thick vertical slit possible in the outer wall?!?

Show the entire bathroom, including the drainage plan from the building file.

Something like that should be with my father, he built the house almost 40 years ago. I am also not trying to throw the entire plan overboard now, the question was just whether the pipe can be laid in the wall. And if I read it correctly from the answers, it’s probably not that easy, at least not without consulting a structural engineer. And therefore I tend more to set up this pre-wall construction. As I said, I had more or less come to terms with it already, but my tiler wanted to "persuade" me otherwise ;)

The question was just whether the pipe can be installed inside the wall. And if I read the answers correctly, it’s probably not that simple, at least not without bringing in a structural engineer.

Structural engineer for that little chase, nonsense. I’d be more worried about vibrating hairline cracks into the pumice wall in the ground-contact area with the Hilti. And without knowing the drainage, I consider this cosmetic operation suspiciously like a Pyrrhic victory.

That is the main sewer pipe, so 100 mm in diameter. That plus 2 cm of plaster needs a "slot" of 120 mm. That is nonsense!

You can't change the connection at the very bottom in the floor slab anyway, so even if you lay it in the wall at the bottom, you would have a bend where the pipe comes out of the wall again.

Trust your bathroom planner and build a wall in front and hide all your stuff there.

That is the main wastewater pipe, so 100 mm in diameter. That plus 2 cm plaster needs a "slot" of 120 mm. That's nonsense! The connection at the very bottom in the floor slab you can't change anyway, so even if you lay it in the wall below, there would be a bend where the pipe comes out of the wall again. Trust your bathroom planner and build a pre-wall and hide all your stuff there.

That is an 80 mm pipe. Above it is the kitchen, that is not a main water pipe. A good 10-12 cm of screed will still be added at the bottom, so I do think the pipe could somehow be hidden there. But you have convinced me, I will put the pre-wall there. I just have to see how big I make it.

And what if you have to deal with that? In an older house, it’s not uncommon for the kitchen drain to be clogged for several meters with fats and the like. The cleanest, simplest, and most cost-effective solution would be an [Vorbau], which is also practical for accommodating the other pipes and creating niches for storage. Personally, I wouldn’t even hesitate!

how far is the pipe from the corner? Possibly if it is 1 m, the shower enclosure is attached to a wall.