Bathroom layout possible like this - distance from toilet to drainpipe

Well, it’s not great, but of course it works. It was done for me too. That’s why I said, it depends on the floor construction. But a DN10 pipe fits perfectly in 10 cm insulation stapler mat + screed. There probably won’t be a window on the ground floor...

The floor construction is 16 cm, with presumably 8 cm insulation. Would that mean that in the entire upper floor the insulation would have to be 10 cm? Did you do it that way? Thanks

Actually, the insulation without the stapler mat (which is also insulation) was 8cm for me as well. For me, the drain pipe from the shower and toilet was routed about 1.8m perpendicular to the downpipe. I even laid the first 8 cm myself. The wastewater pipe even stuck out a little there. The plumber then put the 3cm stapler mat on top, and the screed nicely concealed it. At the neighbor’s place, about 2m of the pipe running perpendicular had to be left out of the screed and boxed in by the drywall installer. Of course, this is not what you want in a new build. But technically, it is possible.

You can also prepare a corresponding "conduit" directly in the concrete floor. Simply press the KG pipe slightly into the liquid concrete and shape the concrete accordingly. Then remove it again and allow it to cure. This way you easily gain 3-5 cm, so that you can later "hide" the 100 mm pipe in the insulation with sufficient slope. It should therefore be unproblematic! Ventilation would of course then need to be led further into the attic in the [Vormauerung].

To my knowledge, a drain is not laid crosswise, it also doesn't fit into the screed. I see the blue cutting point at the window here, but the pipe would also need to be vented....

I would wait until the specialists are back from vacation!
Without the ground floor and so on, this is more than guessing here

The walls on the ground floor are basically shown with the blue lines. There is no window on the ground floor at the blue line, but a sliding door that could interfere. Thanks for the info.

Well, it’s not great, but of course it’s possible. It was done for me too.

"It was done for me too" probably means: without botching? I’m glad they paid attention to short distances at our place, because clogging with such a layout is no joke. I would not recommend such a cross-laying.

Yes. The same attention is paid to the slope as under the base plate or over many meters in the garden. You need a minimum diameter of DN 80 and have to maintain the slope, then there will only be problems if you flush down something other than what is intended for it...