Overwhelmed... Is my calculation/my knowledge correct!?

Where are you guys from? I also come from the area and if the house is not going to be exactly 90m², I would calculate at least €250,000 just for the house, without additional construction costs. Building in the south is extremely expensive..

And why not a local provider? Take a look at Favorit Massivhaus. In my opinion, Favorit Massivhaus has quite good concepts for a tight budget. They offer a lot of "extras", but construction is done with local companies. Otherwise, Allkauf (but Allkauf is timber frame) could also be interesting for you... also very attractive in terms of price. I would stay away from Scanhaus Marlow. I have read not only good things about Scanhaus Marlow.

And as already written here: €25,000 additional construction costs is extremely tight. Calculate with €35-40k and depending on the plot (keyword soil survey) that can also be tight.

In addition to the threads recommended by Yvonne ( ) you can also take a look here:

If you want to build with one of the seemingly cheaper (I deliberately do not write cheaper) providers, I have a very clear tip for you: insist on a preliminary sampling and a calculation of foundation costs based on a soil report (which you will probably have to have commissioned yourself) before signing the contract. This way you can somewhat narrow down two major cost traps, but you will probably also have a different house price.

Your ancillary construction costs are definitely too low.

What often comes up has also often been mentioned here in the forum:

[*]Construction debris disposal
[*]Construction toilet
[*]Painting of the roof overhangs
[*]Applications / permits etc.
[*]Furniture
[*]Costs for mortgage registration
[*]Roof drainage
[*]...

Besides what has already been said here, I would definitely pay attention to the electrical installation that is included as standard. Often, this means 30 outlets and 3 fuses for the entire house... No network, only 1 satellite connection.... I would then also have all of this defined in advance and included in the construction service description/contract before signing. If necessary, also consider whether you want to afford a construction supervisor who can give you important advice BEFORE signing the contract.

The Swabians again

I am always surprised that you buy the land first and then look for the provider.

When the soil is bad again, people complain about how high the earthworks are.

You are 27, how about income / equity? If you already expect the cheapest house?

Addendum to your questions from the first thread:

1.:
I would start by checking out providers online and in model home parks and roughly consider what you want. Construction type, size of the house, number of rooms, etc. Then maybe pick out 3-5 providers to have consultation meetings with. I wouldn’t go to 10 providers, otherwise you won't be able to keep track in the end... So really talk to potential providers and not just "anyone"...

2.:
A lot has already been mentioned. Reading a lot in threads or house-building blogs also helps.

3.:
See 2. It always depends on what you want. I would pay attention to the following: proper insulation/building materials, in a timber frame house a separate installation level, enough sockets, switches and circuit breakers for each floor or possibly every room, insulation values and safety of the windows, good room layout and space utilization, orientation of the house on the plot according to cardinal directions, enough windows for brightness, etc....

I am always surprised that you first acquire the property and only then look for the provider.

But this is also very common here in Bavaria... you can be glad if you get a property and it is at least somewhat in the desired location and of the desired size. Something like a soil survey usually comes only afterwards and in the worst case a nasty awakening