Challenge at a 1/4 circle house ;)

It depends on the development plan, the floor area ratio can often be exceeded by 50% with ancillary facilities such as terraces.

Yes, the original poster could find out whether this applies. That would be crucial here.

Does the garage fully count towards the floor area ratio? My surveying office said no, but I think yes

-> Upload the development plan!

How are grandparents who are more frail supposed to get to the upper floor and keep a 120 sqm household in order?

Anyone who can do that can also continue living in the old house

yes, the idea is that when the parents become weaker, they can come to us and we then have two parties directly.

Firstly, things turn out differently than expected. You have to be able to afford 120 m2 or a quarter of a million just to keep it in stock "just in case"... how about making the project a bit smaller in volume: a small two-room apartment for the parents plus your common room downstairs and your bedrooms upstairs in the converted attic. You should be able to save 50 to 100 thousand easily. And the parents don't have to climb stairs. And nobody stomps around over your beds ;o)

First of all, things turn out differently than you think. Having 120 m2 or a quarter of a million euros just in case in stock is something you first have to be able to afford... how about making the project a bit smaller in volume: a small two-room apartment for the parents plus your common room downstairs and your bedrooms upstairs in the converted attic. You should be able to save 50 to 100 thousand euros without any problem. And the parents don’t have to climb stairs. And no one is trampling over your beds ;o)

In my opinion, that still contradicts itself. Why a two-room apartment for the parents if they haven’t moved in yet? In the end, they might never want to leave their own house. Then you will have wasted money and space completely uselessly.

Extraordinary with a tight budget – here I am at my wits’ end as a layperson. Neither draft has the "spark" I would expect – and I don’t currently have a better idea myself. What bothers me most is that the garage occupies a prominent south-facing spot. That the architect then also built part of the south side with a toilet and a storage room is completely incomprehensible to me. Again about the budget: if the 120sqm section for the grandparents costs around €250K and is not disability-friendly, then that is a potential bad investment. A disabled-accessible apartment could be easily rented for 20 years instead of this investment. One could also buy an elderly-appropriate rental apartment nearby, finance it through the rent, and make it available for the parents as needed for personal use. Building your own home then becomes more suitable for life and more affordable at the same time. I naturally respect any form of life plan, and if the parents are to move into the house, then that is implemented accordingly – regardless of what forum members think. Experienced with “ailing” parents, I paid attention during construction that we ourselves would not have to be brought into the house by our children someday. How it will turn out anyway no one knows. “Ailing” can also be mental in nature – see dementia and its special form Alzheimer’s.