Construction costs for a single-family house with a basement in NRW

I will do that as well. Appointments with architects are already made. But I need to have a rough idea of the prices.

I guess I will keep the plot for speculation and buy one of the houses being built here from the developer. Prices start at 350k without a basement but including the plot. For 170 sqm of living space.
That is still cheaper for me.

From the architect you only get a rough estimate which can be off by 20%, possibly even more. You'll get a number like 400-450€ per cubic meter of enclosed space. Nothing more. You are approaching this the wrong way. You won't be happy with that.

Listen to the people here who don’t want to sell you anything and don’t force you to sign a contract. Under 400k€ without the plot for that level of equipment (and now you’re even asking about KNX) you won’t get away.

KNX came into play thanks to urmel

want to build

Yesterday, I was told by our neighbor that she has to pay €90 for every SINGLE socket in her new condominium that deviates from the standard (in terms of quantity and not quality). I was nearly shocked out of my wits.

You only get a rough estimate from the architect that can be off by 20%, possibly even more. You get a ballpark figure like 400-450€ per cubic meter of built space. Nothing more. You are approaching this the wrong way. You won't be happy with that.

Listen to the people here who don't want to sell you anything and don't force you to sign a contract. You won't get below 400k€ without land with that kind of equipment (and now you're even asking about KNX).

And what do you think is the right approach? I simply don't understand the price discrepancy mentioned here.

I don't understand that either. Why is the developer house cheaper? Because it is 50 sqm smaller than what you described as your dream house. Because it probably has none or few of the technical goodies you want. Additionally, they will charge you a lot of money for your special requests. On the total amount, you will also pay property transfer tax, which is significantly lower (or in your case, not applicable at all) when building with a general contractor or architect on your own land. And that money you have to have in cash; it cannot be financed.

Yes, but how high can the extra cost for a residential/utility basement be? Surely not 80k? With the prices accumulating here, I'm slowly wondering if anyone is still building at all.

Construction costs for basement of a 145 m2 house: 70k + 20k additional civil engineering costs