Building a house is more complicated than thought - constantly new prices!

I will read up on this a bit in the forum. It seems that there really are "hidden" costs.

Indeed. Sometimes there is a "worm" in it, sometimes even a "woodworm". ;) Btw: you catch mice with bacon, but (usually) not future builders.

I have the written offer from both manufacturers here. The only thing I still have to do is lay tiles and hang wallpaper or buy a kitchen. The respective offers state that the house will be built according to the construction service description. - Soil survey - Floor slab - Shell construction with insulation, plaster, etc. - Windows and doors - Roof covering including insulation - Heating - Blow-door test - Room doors - Interior finishing - Electrical and house connections Nothing has caught my eye that might be missing. I also only have to pay after I have received the key to the house and the house has been completely built. This is also explicitly stated again in the offer.

I also had an offer from two providers back then with a price and a construction service description. Do you know what is usually not included there? Qualities, execution variants, and incidental costs. And do you know what that led to? Add a "1" in front of the price of your offer flat-rate already, then you are realistic. I don't mean this mockingly or sarcastically – most people here have already had this experience, including me. That's why I also asked if you are familiar with the revenue model. Cheap advertising prices with flashy-sounding construction service descriptions that only slightly match your own, mostly qualitative requirements upon closer examination. You do yourself a favor by having the matter explained soberly by an expert (or house builder) in your circle of friends. No one here wants to talk you down, but you should listen to the tips and at least think about them.

So I just read through the construction service description of the offer I have again and couldn’t find anything that suggests that I would have to pay more in the end for something I didn’t plan for. Really not! But maybe it is the case that during the construction phase "suddenly" things might come up that perhaps don’t work. But when it comes to quality, I am immediately on your side. I can well imagine that in my case a brand quality is being talked about, but what does that really mean in the end...

No, I don’t see it as someone trying to talk me out of something. On the contrary! I am grateful for this exchange and of course learn a lot from it. I can also come to terms with buying a used house again and then renovating it. We did that two years ago with our already existing house as well. Worked excellently. However, the house has simply become clearly too small by now. And now especially with a child and I also need an office...

I almost think that buying a used house is now the better choice.

So I only read through the construction service description of the offer I have once more and couldn't find anything that suggests I should pay more in the end for something I haven't planned for. Really not! Now, it may be that during the construction phase "suddenly" things come up that maybe aren't going to be covered. But when it comes to quality, I'm immediately with you. Here I can well imagine that although in my case brand quality is mentioned, but what does that really mean in the end...

You can’t properly read a decent construction service description in 15 minutes. Our construction service description had 24 DIN A4 pages in medium font. Reading through it once took about 1 hour after I knew what to look out for. And I went through it multiple times.

I have now posted the construction service description as a screenshot here. Everything is very clearly visible on it. I don’t know, I don’t see any major problem here at first. However, I am happy to be enlightened by other people who have already had experience. As I said, I uploaded the pictures here because I am already seriously interested in this matter.

I have left out the remaining pages. They consist of a cover sheet, signatures, and various floor plans. The entire offer has 28 pages.

...and your idea is that someone now sits down and works out the individual missing / bad points for you?

You have received the same hints from several forum participants. Do with them what seems reasonable to you.