Decision aid for choosing the construction company

As far as the walls are concerned, I have to disagree with you. The mineral insulation with ~25cm is present in all of them that I have seen so far. But then there are differences depending on the provider. Some simply make the mineral wool thicker, some add a second layer, some put 10cm of wood fiber on the outside, and one provider still hasn’t answered me whether they put Styrofoam on the outside. Interestingly, that is also one of the ones that has no details about the wall structure on their website or in the catalogs ;)

Ok.. so then let’s approach the whole thing differently. I have no problem working with regional providers – on the contrary! Of course, you can’t avoid being dazzled by a nice catalog and a tidy website, which might initially convince you more.
So.. regional here means the following providers: Rensch-Haus, Fingerhaus, Streif Haus, Haus and Büdenbender. But I would definitely exclude Fingerhaus for us; we visited their show house several times and were not convinced either by the quality or the consultant. The feeling was just off.
We recently visited Streif Haus. The consultant was very friendly, we got a good feeling. Streif Haus also builds quickly, because they build only a few houses per year. The company is rather "small." They have their own crew. In itself, that sounds good. What didn’t convince us was that they strongly recommended an air-air heat pump, but we would prefer air-water. That didn’t go down well somehow, I don’t know why. Additionally, the consultant openly communicated that he has many partner companies that can take on individual trades, e.g., photovoltaics, floors, bathrooms. This would save a lot of money because Streif Haus would then not have the “problem” with warranties that you would otherwise have to pay for. Okay.. that sounds somehow good but also confused us. How do you rate something like that? Overall, as a customer, you would save a lot of money this way, as was already mentioned regarding photovoltaics, but this tip seemed strange to me?
We have had no contact with Rensch-Haus and Büdenbender so far.
What bothers me most is this aspect of the wall. For example, Streif Haus builds with a vapor barrier. All others are diffusion-open. Of course, Streif Haus says that is better. In your opinion, is this topic even relevant or is it more a matter of belief?
And regarding the construction again: is that even relevant? All have good insulation that meets the KFW40 standard, but the U-values differ. It has already been criticized here that afterwards only the “clueless” pay attention to that. Still, points like whether a screw goes through the vapor barrier or not remain unclear to me.

So.. regionally, the following providers are present here: Rensch-Haus, Fingerhaus, Streif Haus Haus and Büdenbender.

By "regional providers" I and probably most other discussion participants do not mean that they have some company location (headquarters or factory) in Hesse, but providers who do not operate nationwide and are from the vicinity of the construction site, so about an hour's drive around your property. But earlier, I missed answering your question

Is it worth contacting "Fertighausexperte"? Or is that marketing?

to answer:

I have already written about the "Fertighausexperte" here: and here: and consider its specialization quite useful at least as far as we are talking about timber frame prefabricated houses, those with masonry walls differ conceptually hardly relevantly from their locally built counterparts.

By "regional providers" I and probably most other discussion participants do not mean that they somehow have a company location (headquarters or plant) in Hesse, but providers who do not operate nationwide and are from the vicinity of the construction site, roughly about an hour's drive around your property. But I had just missed answering your question earlier:

I understand, but honestly, as far as I have researched, there are not many other companies here that primarily operate locally/regionally. The companies based in the immediate vicinity that build prefabricated houses also operate supra-regionally.

Search the Internet for keywords like "general contractor Hintertupfingen," "turnkey construction Hintertupfingen," etc. We got quite a long list just from the 3 main nearby towns (plus some automatically generated websites...). I then contacted two of them; unfortunately, one is already fully booked for next year, and the other apparently has such a good workload that I didn’t even get a reply. In addition, I asked everyone I know, including from the sports club, etc., who has anything to do with construction sites and actually got a tip for a company that I otherwise would never have found. To be continued, next week we have a meeting with them. By the way, according to their website, they do timber frame construction as well as solid construction, just like the company that declined us because of a full order book.

but to be honest, as far as I have researched, there are not many other companies here that operate primarily locally/regionally.

Then simply put your belief to the test again that all the solid builders demanded too high a surcharge for the desired KfW level. KfW40 is not rocket science, but rather something that can be developed modularly if you regularly offer KfW55.