Single-family house with 135 sqm living area plus basement with integrated garage/office

This plan looks habitable and well thought out. How do you like it?

I will post a second floor plan shortly (it comes from an architect)!

A quarter pound more measurements wouldn't have hurt.

How much buffer do you have? For the remainder and the outdoor area? By remainder I mean, for example, there is still easily another 20k€ missing for plumbing, a new platform staircase as a flat stringer steel version with oak steps also costs about 20k€ and so on.

How much buffer do you have? For the rest and the outdoor area? By rest I mean, for example, there are easily another 20k€ missing for plumbing, a new podium staircase in flat stringer steel construction with oak steps also costs about 20k€ And so on.

What do I have to plan for? I actually assumed just under 2000€/sqm plus basement (60,000€) ... that would be 270,000€ for 135sqm plus 60,000€ for the basement ... somehow this is taking on different dimensions!

Where did you get the numbers from the cost breakdown? You can deduce yourself that something doesn’t add up. The controlled residential ventilation alone costs around 13-15k€ gross depending on the sanitary company, 3x bathrooms, piping and heating with 39k€ is a bit strange to calculate. We have 2x bathrooms and a good but normal bathroom equipment without a tiled shower or built-in fittings and ended up at 52k€ (the offer is now 3 years old).

The 2000€/sqm are also figures I calculated 2-3 years ago. Today you can count on 2200-2300€ and I strongly doubt whether the basement should be valued at 60k€ due to its type of use. Maybe it would be good for your calculation if you also apply the 2200€ in the basement.

I think the error in the calculation is in the basement. Those are living rooms for you. So normal room height, underfloor heating, electrics. Why should that be cheaper than your above-ground living space? Better assume 2000 per sqm. The garage partially integrated like that is also not the cheapest solution. Thermal separation is necessary there. So generally calculate every sqm of finished living space (also in the basement) at 2000 euros + garage + incidental construction costs + outdoor facilities + kitchen \ other furnishings

And your title 2 in the cost breakdown should be shell construction + earthworks? That will never be enough.