Floor plan design city villa with basement improvement suggestion?

Electric could be possible. The standard is only 4 sockets per room and one light switch. In the hallway, push-button switching with a burning point, etc. I think for this 1950s installation the price should fit and that’s how the architect calculated.

For minimal equipment it might be enough, but hardly for a sensible and contemporary installation (and I’m not even talking about KNX).

And I would also like (proper) parquet for 1600 EUR

@hampshire is building with similarly aged children

But only the age "fits" – rather not translatable to a standard plot.

Exactly, @hampshire has a suitable concept. It’s also not a big deal if the children are still there in 10 years.

Yes, more or less a granny flat, and thus not fundamentally different from the mother-in-law extension at – only at aligned in the same axis of the house; neither can be represented like this on a standard plot.

In the upper floor, we planned the large children's room so that we can divide the big children's room into two rooms and use one as a guest room or dressing room.

But you can’t simply separate it because of the door and window positions.
For me, some window and door positions were set without much thought, for example in the storage room on the upper floor: a 60 cm deep built-in closet behind the door would be optimal, but that would block the window.

The idea later is that one of the kids might take over the house and my wife and I would downsize technically from the house side.

Why should one of them inherit the house and not the other?! That will only cause hard feelings. Also, an inheritance doesn’t justify a granny flat.

However, the two rooms wouldn’t be big enough....

I have to mention that as a child you need more play space on the floor, whereas as a teenager or young adult you need more storage space. Over 30 square meters is much too exaggerated. At some point, a room is saturated in size and can only become uncomfortable. Also, such a narrow layout isn’t nice.

I consider the rooms unplanned: on a large area, simply partitioned off. Not even the wardrobe is built in. The result is rooms that extend the whole length of the house, the child in a difficult age sleeps next to the parents, the stairs are in the entrance/dirt area, the kitchen is simply impractical and cannot be separated if necessary.
Basically, it is an inflated standard town villa with basement. Not that town villas are bad, but here there is absolutely no planning that I could expect in 200 sqm.

We were in Canada in a B&B that was planned so that the three children's rooms were used as guest rooms

That can be done if it’s well planned.
However, the guests then usually have to eat in the matrimonial kitchen and disturb the marital peace.

Unfortunately, I don’t see the basement here; it wasn’t shown to me.
But it’s not important to me either, because it’s actually unnecessary. A beautiful house with two levels, where two children’s rooms of 15–18 sqm each with the utility rooms in the basement form a later granny flat, makes much more sense.

Thank you very much for your tips and the constructive criticism regarding our construction project. I would like to briefly address the points budget / cost estimation for our building project. We spoke in advance with many prefab house companies (solid construction) that are priced rather in the upper segment. All these prefab house companies offered a fixed price of about €325,000 - €350,000 for a comparable house. It must be mentioned here that no floor coverings, house connections, garage, and earthworks were included. We consciously decided against the prefab house companies because all of these companies wanted to conclude a work contract first and then only go into architectural planning discussions. Therefore, in my opinion, the pure house price of about €350,000 is feasible.

I myself am also of the opinion that some trades in our current cost estimation are set a bit low; here we will see if it actually turns out that way.

But in my opinion, one is significantly more flexible when awarding the trades individually oneself. This way, you can juggle a bit with prices and trades.

But in my opinion, you are much more flexible if you award the trades individually yourself. This way you can juggle a bit with the prices and the trades.

I think it's good! But I still have to agree with my predecessors, some of your prices are set too low. What do you want to do yourself (apart from the earthworks)? Do you live near the construction site? Do you have someone who can check regularly?

The offers from the prefab house companies probably won't include sanitary objects,... right? I don't think you'll settle below 400,000 with the current plan.

What I really don't like about the floor plan at all is this tube-shaped kitchen. Do you maybe already have an updated plan from your side?

The offers from the prefab house companies probably won’t include sanitary objects,... will they? I think with the current planning you won’t get below 400,000.

In the offers from the prefab house companies, except for the planned WC and shower in the basement, everything was included like that.

What I really don’t like about the floor plan at all is this pipe-shaped kitchen. Do you perhaps already have an updated plan from you currently?

Unfortunately, we have hardly any leeway to redesign the kitchen here, as these are load-bearing walls (yellow).