Floor plan of semi-detached house 135m2, two full floors

I don't like the bathroom upstairs at all: dark washbasin, shower by the window: I would swap the shower and toilet and replace the bathtub with an asymmetrical one measuring 90/160cm.

I completely agree with that.

What is usual anyway?

Usual is what the majority does (personally, I don’t know anyone who has their main access to the garden/terrace through the kitchen. None of the construction projects I have supervised in recent decades had such a solution as standard). Which does not exclude an unusual solution. If it suits the OP, then it’s okay. There’s no need to insist on what’s usual ;)

I don’t see any major flaws now, except..! But in the kitchen it’s not an island, that should be noted. Shower on the ground floor, does it have to be there? It’s already very, very tight under the stairs. Utility room accessible from the living room, there are worse things. I would work with a hidden door there. I don’t like the bathroom upstairs at all: dark vanity, shower by the window: I would swap shower and toilet and replace the tub with an asymmetrical one measuring 90/160 cm. Also: I would use the front door as a terrace door and make the kitchen accessible right after the 70 cm wall stub. Then make the kitchen a U-shape, with the countertop along the bottom of the plan and going into the U. A wide tilt-and-turn window at countertop height by the terrace, and the vacation can begin. What is the deal with the stairs in the upstairs bedroom?

Thank you for your ideas. We would like to keep the hallway spacious and separated; with two children we simply have too much stuff. The stairs in the bedroom are rather planned for the distant future, when the children have moved out. Then a permanent staircase to the attic could be planned and one of the other rooms used as a bedroom. Regarding the bathroom, that’s a good point, we will take another look!

You don't have to harp on "usual" ;)

I'm not harping, I'm explaining to you. But maybe someone will come along who harps on the "one" ;)

The staircase in the bedroom is planned more for the distant future, when the children have moved out. Then a permanent staircase to the attic could be planned, and one of the other rooms used as a bedroom.

I would reconsider that. In the end, no thermal insulation under the roof is planned, and even with windows, space is limited with a hipped roof. Therefore, there is no escape route under the roof. And when the kids are no longer there, you have enough living space anyway – and probably enough junk stored up there as well.

Thank you very much for the many responses and impulses!

Regarding the attic: we would probably never use it as living space, the idea was that a fixed staircase might be nicer than the typical folding ladder when we are 70 and not as sure-footed with a box under our arm. With the changed roof pitch, about 15m2 with standing height should be created upstairs.

Bathroom topic: we plan the masonry wall up to a height of 130cm, above that a glass wall. Do you think it is still too dark at the washbasins?

Terrace in front of the kitchen: I see opinions are very divided there. For us, however, we think it fits well, a lot of our life takes place in the kitchen, the kids running in and out doesn’t bother us and yes - we hope to have a little peace and relaxation in the living room someday without someone walking through every 3 minutes.

Staircase: Yes, unfortunately it is kept as space-saving as possible, we need the space downstairs for access to the guest WC and definitely do not want to give up the large hallway in favor of an extra room there.
In addition, the staircase should end downstairs in such a way that you can look into the garden or the living room.