Relocation of a 60s bathroom to a new room, 12 sqm floor plan

The plumber said it would probably be possible to connect the wastewater pipe to the pipe in the laundry room floor with a ceiling breakthrough in the basement.

It would certainly be helpful if the toilets are roughly aligned vertically. Maybe you should generally indicate in the "new" bathroom layout plan at which points in the basement the toilet drain pipe and the water drain pipe are located/running.

I quite like the idea of the integrated mirror on the pre-wall as well. Do you have any experience with how it is when, for example, the shower is illuminated?

No, no personal experience. With identical lighting in front of and behind the mirror, there shouldn't be a problem.

Also that we can either install the glass pane flush towards the shower or towards the washbasin. This leaves some space for toothbrushes, etc.

We installed a glass wall (without a mirror) centrally on the partition between the shower and toilet in a T-configuration. The partition is quite wide and storage space was created on both sides. I have no personal experience with flush edge mounting. I probably wouldn’t try it completely flush to ensure maximum edge protection of the pane. I would allocate most of the resulting space to the washbasin side.

The shallow floor night light could maybe also be installed as an LED strip under the bathroom cabinet, then we save some effort with integration.

That works of course as well. An LED line under the tub is even more suitable here, as it conducts light better.
Are you also doing the hallway? The same feature is practical there to get through safely without fully waking up. Put it in the baseboard...

Do you recommend planning the shower a bit shorter than 160? Or rather let the washbasin run the entire width, from the wall to the end of the shower?

I see it like (as so often with) . Better to keep the shower partition a bit longer than the washbasin. The mirror wall doesn’t have to be extended to the outer edge of the partition wall. That small corner is perfect for a stylish waste bin – e.g., the Omnioutil Bucket from Hachiman – great quality and a design like a sculpture.

The shape of the bathtub is of course a matter of taste, but it probably brings you more disadvantages than advantages.

As a self-proclaimed non-expert on bathtubs, I found the shape appealing because you can sit quite comfortably in it and it has two “backrests” to a “foot section.” Maybe I only see it that way because we don’t have a bathtub and instead sit around in the small whirlpool on the lower terrace to relax – just like you suggested.

Maybe you should generally mark in the "new" bathroom floor plan at which locations in the basement the toilet drainage pipe and the water drainage pipe run.

Valuable hint. For the ideal bathroom, I’d also accept a few visible pipes in the laundry room – of course it’s nicer if it can be connected easily.

I have no personal experience with flush-mounted installation.

I can report from experience; we have had it done twice, installing a panel flush on the desired side. A skilled craftsman from this area can manage that. But if the wall is wide enough, you can consider whether and what you want to provide as a shelf on one side or the other. I definitely find it an extremely sensible matter and one of those small, important details worth taking time for, which you can enjoy later.

As a self-confessed non-expert on bathtubs, I found the shape appealing because you can sit quite comfortably in it, and it has two "backrests" leading to a "foot section." Maybe I only see it that way because we don’t have a bathtub and instead relax in the small whirlpool on the lower terrace – as you also suggested.

That comes from my favorite quote of a sadly recently deceased friend: "What is often is often, and what is rare is rare." I understand the idea regarding a shared bath with the toddler but think one should somewhat detach from that since the little one also quickly outgrows this age. If the adults like to bathe together, then that’s fine, that is a lasting advantage, but I wouldn’t focus on something like that just for 2–3 years which could later become inappropriate. To be honest, we implemented some such things in our first house that quickly became obsolete and were rather annoying. If you also bathe together (which is less relevant for me), then I would look for the exactly right two-person bathtub and the little one could enjoy that for the next 2–3 years (and then again from age 12 upwards with their girlfriend...).

Maybe you should generally store in the "new" bathroom layout at which point in the basement the toilet drain pipe and the water drain pipe are located/running.

The pipes under the room are of course already an issue. The laundry room has a sink on the left as well as a connection for a washing machine. In the middle of the room there is a drain embedded in the floor, top right a shower, bottom right a toilet. The shower is more of a luxury problem, we would basically like to keep the toilet.

The question is whether it is even possible and also financially justifiable to move the toilet and place it top left in the new bathroom. For the bathtub, the position is probably favorable since there is a shower underneath. The shower could presumably also be placed towards the sink. For the toilet, the pipe is probably too thin. I tried to illustrate this once approximately with a red square (represents the basement wall). An entrance door to the room is left of the toilet. I have attached the floor plan of the basement level. Since we have to renew the water and heating pipes anyway due to their age, the water connection is not the problem. Wastewater could be tricky, though. Does anyone here have experience whether the wastewater connection of the house runs through the floor? The plumber said you could break it open and possibly get to the pipe. It probably won't be cheap.

If you also bathe together as a couple (which is less of an option for me), then I would look for the exactly right, two-person tub and the little one could enjoy that for the next 2-3 years (and then again from 12 upwards with the girlfriend...).

Absolutely right. :) We actually often sit together in the tub. But with normal tubs, it’s always a bit cramped.