Single-family house - Design planning - Request for feedback

even if in your opinion everything should be demolished,

No. It can certainly be useful – I have no reason to believe that it is not fit for purpose.

and I try to make the best of it.

That's precisely why I warn to keep an eye on economic viability – so that you don't "save" expensively.

not that you "save" expensively

That’s why I am also trying, with your help, to come up with a decent floor plan. Only then can I have a sensible conversation with the construction company regarding the costs. It’s pointless to discuss prices with the construction company now, if the floor plan will be changed again in two weeks.

Sorry, but you seem to have misunderstood some preliminary information.

It's not the floor plan that determines the prices, but primarily the size of the building and its features.
You have certain ideas about the features, but you are fixed by the foundation slab when it comes to the size of the building.

Your foundation slab is 12.50x12.50 = 156.25m². With 2 full floors, you initially get a volume of ~1400m³. You still need a roof, but I'll leave that out of the costs for now since you already have the groundwork + foundation slab done.

At €400/m³ I come to €560,000. At 230m³ and €2200/€ to €506,000k. The truth is probably somewhere in that area.
But then there are also outdoor facilities, a double garage including (!) storage room, and some ancillary construction costs.

I stick to my point: in the end, the construction project costs something starting with a 6.

So no offense, but to hear here that construction costs should not be discussed, while initially planning with €400k, makes me doubt whether you are even aware of the matter.

If not, you should stop planning castles in the air.

For a meaningful offer, in these dimensions it no longer matters whether you have 120 or 140 linear meters of interior walls, but purely the cubic volume.

If you can also cough up €600k, all good. Otherwise, ditch the foundation slab or go for a bungalow/stepped floor to reduce the cubic volume.

Hello Matte1987, thank you for your explanation. I am aware that we are by far no longer at the originally stated 400k€. That is also why my contribution was that the costs should be left out of the discussion about the floor plan. The goal is to create a decent floor plan based on what exists. I need this to be able to have the final discussion with the construction company.

The goal is to create a decent floor plan based on the existing one. I need this in order to conduct the final discussion with the construction company.

What do you expect from the "discussion"? - that the construction company says: Your unwavering loyalty to the oversized foundation slab moves us to such great crocodile tears that we will generously give you all the resulting surplus building mass for free?

If the house ends up costing 600,000 EUR instead of the planned 400,000 EUR due to oversizing, then keeping the supposed valuable item "foundation slab" only made economic sense if it was worth more than this difference of 200,000 EUR. And at exactly this point, even a beginner should see question marks in more than just the usual amounts.

A one-and-a-half-times expensive house simply means a one-and-a-half-times longer financing period and very roughly about a fourfold risk of becoming unemployed or unable to work before the loan is fully repaid.

In your perception, the foundation slab is probably symbolic of the dream house goal; from my point of view, it is the coffin nail of its financing.

Nothing against your wonderful foundation slab. Unfortunately, it only fits a builder who can finance a (excluding garage) 230 sqm single-family house without any ifs or buts. And who can say: my family needed a 170 sqm house, we had to allow ourselves the 60 sqm excess because the foundation slab predetermined these dimensions. If you are that person, I have nothing to say.

What do you expect from the "discussion"

I expect/hope to put together a proper house from the discussions and the resulting advice, which also radiates a certain modernity/spaciousness/coziness.

If you are that person, I said nothing.

I mentioned several times that the financing should be taken out of the discussion. What exactly do you want to read? Yes, we can afford the prices. At that time, I had entered the 400k€ because we didn’t exactly know what such a house would cost and also wanted to get your opinion on the first floor plan back then. Therefore, once again my question to the group: Would you like to help me put together a proper floor plan with the help of your experience, without discussions about the costs/financing?