Who or what is Konvent?
If this is allowed in the forum, I would be happy to post the builder here, but this will only be known to people from my catchment area.
I repeat, the location is personally the most important thing to me, and there are reasons for that, personal and family-related, and I have also treated myself to all the extras that I would have gotten in any other house. I could have bought a house that is just as expensive in an expensive location, but I want to have a house exactly where the house is now being built.
I have looked at many houses recently, old and new, and really very few had underfloor heating. In the house where I live now, built around 1978, there is underfloor heating on the ground floor, but no underfloor heating on the upper floor.
A mix of underfloor heating is not more expensive, I have inquired with my builder and am happy to repeat myself. (Or is the maintenance meant to be more expensive)
1. NO underfloor heating 0€ extra charge (sounds logical, only other or additional radiators cost more, also logical)
2. Ground floor underfloor heating and all other rooms and floors radiators cost 8,400€ (The two mixing circuits make sense, it is also like that in the house where I live now.)
3. Ground floor underfloor heating 8,400€ + 1st floor underfloor heating 1,000€ + attic underfloor heating 1,000€ + basement underfloor heating 2,000€ (the basement is apparently more work, hence the higher price)
So that would be the 8,400€ surcharge when mixing heating types to 12,400€ if there really were underfloor heating everywhere.
Normal radiators are definitely enough for the basement for me, I know no one who has underfloor heating in the basement and on the first floor the heating is hardly ever turned on anyway, since there are only bedrooms and a walk-in closet, and I have an open gallery from the ground floor to the first floor and the heat will surely rise well there. To be honest, I have no use for the attic yet, it could, for example, become a children's room.