Floor plan design single-family house approx. 240 sqm with double garage and basement apartment

Leave out the UG, then you will also stay within the budget. Where can one see the height difference of 1.5 m?

Good evening, thank you for your quick feedback, I will address it right away:

I like it.
The granny flat needs a storage room.
The bedroom becomes too stuffy - I would omit the south window. We have that (unfortunately).
Be careful that the pantry does not become too narrow.

[*]Thanks for the hint about the granny flat, for example the tenant’s washing machine would have to go there
[*]Really completely closed to the south in the bedroom? We will reconsider, maybe a window solution on the south/east corner
[*]What would be an still "adequate" width of the pantry?

I wouldn’t worry much about the street, it doesn’t look like a highway. In my opinion, you didn’t overlook but rather committed the major planning mistake: the blazing sun from the south is brought inside, and the evening sun in the west is ignored; as well as the garden on the quietest east side.

[*]The main through road in the village is on the west. There is quite some traffic but clearly no highway.
[*]We would of course like evening sun in the west, but that is the only place where the entrance to the granny flat could be.
[*]The garden on the east side extends another 11m beyond the building boundary. I thought that was clear from the plan - where do you see the planning mistake here?

How does that financially add up??

[*]Yes, that is our problem. Hence also the core question in 130 characters ;-)

And why do you still need the granny flat? If you are already 125K in the red now, you should urgently question the architect. Who plans like that when the requirements are clearly not met? Note: construction projects rarely become cheaper (but very often more expensive) than planned.

[*]The granny flat is initially planned for rental. Later, an elderly family member could be cared for there.
[*]Regarding costs: You are right, the cost estimation just came a few days ago – now we will enter into a discussion.

At this size 600k is simply completely unrealistic. Personally, I also consider the architect’s estimate very conservative.

[*]With the current developments, that is certainly correct. What would you consider a realistic estimate for a multiplier over the gross volume?

Omit the basement, then you will also stay within the budget.
Where can one see the height difference of 1.5 m?

[*]Interesting idea without basement. But then the granny flat would have to go somewhere else?
[*]The height difference is actually estimated. Surveying has not yet been done and the height points have not yet been taken.

Basically a nice floor plan. However, I do not like the size of the children's rooms on the upper floor; I would rather see them at a total living area of 18 to 20 sqm. Personally, I do not like a study on the upper floor. I would sacrifice it in favor of larger children's rooms and a bigger children's bathroom, if it is not absolutely necessary...

Interesting idea without a basement apartment. But then the basement apartment would have to go somewhere?

You should be made aware that you cannot afford the basement apartment. In this respect, the question is moot ;)

Then the granny flat would have to go somewhere?

The reason I asked is: You have to be able to afford a granny flat, and it is a widespread misconception that it would contribute any cost coverage to the main apartment. If you don’t need it now, then don’t build it – or find someone who will pay for it (entirely).

You want to get into debt by 125k too much to rent out a basement apartment? (If it's still enough, I would also expect even more for the project.)

Would have also said to leave out the basement completely.