Floor plan V1.0 - 230m² private home for 3-4 people

There should still be enough space in the laundry room here.

In this draft, yes, but if we calculate backwards from the budget, then you have to give up about 100 m² of living space. That would probably put pretty much everything at risk.

- Square meters: The goal should be to plan <180sqm here.

Even then, without immense personal effort, you will not reach the budget you have set.

- Stair width visually between 80-100cm, although it makes sense/there is space to go wider here.

That is not only sensible but in my view an absolute standard as of 2021.

There should still be enough space here in the laundry room.

Then draw in everything you need. House connections, fuse box. Hot water, heating technology

What is actually your goal? Entertainment of the forum? Getting rid of your corona boredom?

- Building services go into the laundry room

Given the room dimensions (width < 2m), it can no longer really be called a laundry room .. especially with an ironing board etc. If you do a lot of home office and sit in the farthest corner of your house, also consider the distance to the coffee machine/drinks, front door (if the postman rings three times ;)) etc. Retreat in the office should be possible with a closed door, also as a signal to the family "work is happening now". EDIT: Planning walls on top of each other is already good, but this should not be followed slavishly and should not completely determine the upper floor.

I can only agree with YSOP...

That can’t be serious with that budget...

25 m2 children’s room? The hallway + light space?

Go into a 6 m2 guest bathroom... that’s not generous, you feel lost in there...

How big are your current rooms, develop a sensible room concept based on that.

Garage belongs next to the house for me. Better thermal separation. And the car brings moisture (Karlsruhe = often slushy snow?).

oh yes... the plot would be great.

If things go badly, you will need 350,000 € alone for the plot of land in the Karlsruhe area. At least for the house and on the open market. The last area I know of here where the municipality sold plots sold from 602 €/sqm for detached houses (plot approx. 500 sqm) including development. Privately, plots are sold from 1,000 € per sqm.