Decision aid for choosing the construction company

It has already been mentioned here that the best wall is useless if a thin door is installed. So rather pay attention to the overall concept than to individual details. And if a certain soundproofing is important to you, then have it planned and compare.

Doesn't anyone else here think about the walls? Am I attributing too much importance to that? Especially concerning sound, the structure is relevant, isn't it?

I hoped you had understood by now: Structure is theory and workmanship is practice, but only the latter makes the product complete (and is only to a very limited extent representable in the "engine maps" of wall structures).

You can search for sound transmission in semi-detached houses here. Some people have problems when there are sound-transmitting components. The best general contractor won't help if it's not built correctly.
I will soon be moving into my fifth own property (from condominium to semi-detached house to detached single-family house). Only in a condominium from the 60s did I hear my neighbors. Otherwise, there were never any sound problems - all solid constructions (also interior walls) made from different materials around 1900 / 2004 / 2014 / 1967.

You are lucky. In my case, the record is rather the opposite; the only place that was somewhat okay was my parents' house (but that's easier with a detached single-family house, of course). In the apartments, I always somehow heard the neighbors, and here (apartment block from the 80s) you can hear voices through the ventilation system in the bathroom. Problems with impact noise and voices through the concrete ceiling as well. Personally, I can live with it; my girlfriend is bothered when the neighbors have the TV on at night.

Don’t worry about the wall structure, but about the characteristics of the house,

Very good tip! Chapeau!!!

For all variants, whether building materials, windows, etc., there are always pros and cons and rarely “the right one.”

Yes, there is not just “the right one.” That’s why there are no answers to your questions.

Doesn’t anyone else here think about the walls? Am I placing too much importance on it? Especially regarding sound insulation, isn’t the structure relevant?

Of course. Most homebuilders build according to recognized rules of technology. That should be sufficient unless you are very noise sensitive, want to build near an airport runway or railroad tracks, have a three-lane road next to the property, a kindergarten or school as a neighbor, can only tolerate music without background noise, have a yipping dog, or are bothered by clucking chickens in the village, etc.
No one has problems with any wall structure except where duplexes were sloppily built, the DIYer did not heed floating floor installation, or the old vacuum cleaner runs every day behind a cheap hollow-core door.

The building methods must know what they are doing. They can’t have every second house rotting away within 15 years.

Yes, but the builders are also confronted with regular ventilation, which is often answered with “yeah, yeah.” Afterwards, people are surprised and speak badly about the company.
Also: even the most expensive and ecological homebuilder can end up with a “mold house.” Experienced even with neighbors – for 9 months wall claddings were drilled open searching for the stove...

So what to rely on? The contacts at the prefab house builders are the only ones who plan the entire house with you. :/

Yes, but you chose them as a partner to the best of your knowledge and feelings, didn’t you? If you have doubts, then build with an architect whom you can pepper with questions every day.
With a general contractor (whether wood frame or solid construction) you have to be able to rely on something. Reputation is very important here, for example also reference buildings, as mentioned.

I currently live in an old building with about 40 cm thick exterior walls. And I hear almost everything from outside. Any thinner, modern wall is better in soundproofing.

Great, isn’t it? Nowadays you will definitely be building a house with a modern wall ;)

Also e.g. the point: vapor barrier. With some providers it is inevitably pierced when screwing into the wall, with others not. You read about this: terrible, everything molds or totally irrelevant..

Well, then those walls are out for you.

Don’t make life too difficult. See above: “the right one” does not exist. Only different.

Anyone who immediately commits to things like KFW standards, a specific roof shape, wall structure, or similar cuts themselves off from potentially very interesting things. A house is a construct where so many things work together and feel completely different from the perspective of each user. I believe, as a future builder, you are looking for maximum security and in my opinion rely too much on buzzwords in the construction sector, which are sometimes used in a phrase-like way. Ultimately, you can build a great house without Kfw (after all, you only want to build a "normal" house) and then live more resource-consciously than anyone else who has built a KfW-XY house. You yourself are the one who can control that through your habits. An energy saving regulation house can be lived in nowadays with very little energy. I didn’t want to build a Kfw house, but now it probably results from things I would have wanted anyway, possibly even Kfw40. But I am not chasing any such standard.

therefore, for example, we are committed to a KFW 40 Plus house

I would first look for my possible floor plan that fits my plot. Even better, a sharp architect, who will also find the right craftsmen and clarify other questions.

I am attached to Viessmann

Better don’t be attached to anything, then in the end it can still be Viessmann. I had a Viessmann heating system for 30 years and it was good, but why should I stick to a particular manufacturer for a new build?? Check why you are so fixated on such things. This is something people here want to convey to you.

For us, an important thing is a good photovoltaic system with at least 7-8 kwp.

That also comes at the end... maybe it will be 15kwp or you will come to a completely different decision. Things build on each other. Yes, you would like to use photovoltaics optimally, okay. Remember that and implement it later in the process, but don’t build the house according to photovoltaic specifications.

So... on the topic of KFW40 Plus. We just want that. Out of conviction.

What conviction is that?? With Kfw40+ you get more subsidies, okay, but usually worse interest rates... what is the conviction? You can do it, but Kfw40+ does not necessarily mean a more ecological way of building at all.

Whether that is smart or not, doesn’t matter, we want it, even if it might cost more. It’s true that many solid builders are off the table because of that, but Viebrockhaus, for example, would be possible.

No; even if it’s unwise, you would do something because you want to, I read. Hmm... I would rather not do that. What is the exact motivation for it? Maybe there are other or multiple ways to get to Rome. Kfw standards did not come about only because of ecological thinking...

I want, as silly as it sounds, simply to build a house.

No, that’s not quite right. You have certain and also "high" demands (understandably!!!) and therefore you have to put in the work to search, check... if it were "just any house" it would be done very quickly. [/QUOTE]

By doing this, we would save a lot of money because Streif house would not have the “problem” with warranties that would be charged. Okay... that sounds somehow good, but also confused us.

I would be very careful with this statement

I think the problem is that there are simply very many people here with very different ideas, opinions, financial possibilities, and expertise.

?? Yep, but that’s an advantage and not a disadvantage??

Focus here: photovoltaic system should be well oriented.

That also comes later or are you building a solar park in which an inhabitable ES is then located? First the house with your very special floor plan!!! Then such things. The order is different.

With nearly 3 children, soundproofing is very important to us.

That is too general. How is your plot? Do you need soundproofing from outside because you live in the flight path or your neighbor is a known drummer, or do you rather need soundproofing between rooms INSIDE the house? Do I need protection as parents from children’s noise or sleeping children from parents or TV noise or or or... There is no ONE soundproofing just as there is no ONE house.

I have seen that the ceiling thickness is sometimes very different. Viebrockhaus, for example, with 16 cm compared to 25 cm with others.

I had a solid house with 25cm concrete ceiling. If you have the bedroom underneath and someone walks normally above, you hear it, especially at night when everything is quiet. If it’s your own children or parents, it can be nice; if it’s a noisy tenant, it annoys you. Therefore, I believe that initially a plan that fits your plot with a nice, individual floor plan would be an entry point for you. Then many prefabricated house builders will probably drop out or become too expensive. For example, it is very important to me that I can decide many things individually without the price exploding because of it or the general contractor complaining. So I searched intensively for that. I want to decide heating, technology, details etc. myself. You are worried about noise, so clarify what kind of noise it is and design your floor plan in a way that you avoid certain things by the location of rooms; that could be an architect. Then in further planning you can adjust structural things like double boarding, doors etc. I have now read all this and advise you to let go of everything again from Kfw40 to Viessmann and first create a possible floor plan yourselves or go to an architect. Whether it is then built in timber frame or solid is usually irrelevant.

Weren't the same questions already asked in this thread last week? You are going in circles... you are mentally stuck on the questions of the right wall and soundproofing instead of finding your little house. Maybe someone here should just ask how those who have already built found their general contractor or architect and what they would pay attention to for the next house, meaning what they would do differently. Of course, not the equipment, but when choosing the general contractor.