Tiler costs 200m² new construction

Then good luck. But don't wonder why the bathroom may now be more expensive. As already said, "Muschkalkulation"

I am aware, but 40k€ is a different ballgame. Thanks again, when I think about it I will post a visual of my skills in a year...

And whatever you do, don’t build the stairs yourself! Your wife must also be clear that it can look awful in the visible area. That means she also has to leave 5 degrees for her kitchen.

I would be interested in a report of experience.

No, stairs are not done by me either, so stairs and the large bathroom are done by the tiler.

As far as doing it yourself is concerned: years ago, at my parents' place, we tiled the basement ourselves "for fun" (only storage and heating rooms) because my father happened to get the entire stock of a former tiler for free. Just for your information, he is a craftsman and is not clumsy. The result on the last walls is okay, also because the tiles were rather small format, max. 30x30 cm, but in my own bathroom I would rather not have that. The first walls really were not great, so the learning curve is really very steep and on the first... let's say... 20 sqm to 30 sqm you basically only produce visual rubbish. Even tile spacers and taut strings do not necessarily make the joints straight. Then all the breakage that an inexperienced person causes when using the tile cutter. Think about it carefully whether it really can't be done financially any other way. Or, you have a training area somewhere and first tile, for example, the garden shed at a friend's place, then your utility room, and only then the bathroom. That might still be doable.

I have planned it so that I start with the extension (not included in the 200m2), that is already a good 85m2, I think you can get a good estimate there whether I have talent or not, if not, only the ground floor will be tiled, the rest will be laminate or parquet.