Sound insulation VDI Guideline 4100 & DIN 4109 in prefabricated house construction

Thank you for your opinions/contributions, (especially for the detailed message from MayrCh).

The 0815 manufacturer did not want to have this dictated in the contract... as mentioned, there was talk of "the possibility of additional measures" to achieve improved sound insulation within the building (diamond plate and sound-decoupled ceiling). So without a dedicated architect.

No detailed information about the neighborly partition wall regarding sound insulation. Fire protection class F 90 B.
Since two semi-detached houses are being built (so two walls "next to each other" and the partition wall in between), it is said to be "in any case sufficiently soundproof". In the end, it's all sound and smoke, and then it's too late, which is why I keep harping on it.

Unfortunately, as a layperson, I really cannot assess the competence of the planners, so the approach with the acoustician could certainly make sense. An extra 5,000 euros won’t make much of a difference anyway. Interesting hint!

I am still looking for someone who has done something like this themselves:
Optimizing timber frame construction with an external building acoustician (if yes, with whom, etc.)?
Has anyone ever been so "crazy"? Could this possibly be completely over the top?
I want to make sure that in the end it is experienced in everyday life without any "teeth grinding".
After all, I will likely (optimistically) live there for another 30 to 50 years.
Sound perception is certainly subjective, so I would like to ensure measurably good results. This is not so easy with prefabricated timber frame construction, is it?

My father lives in a solid semi-detached house and gross errors were made regarding sound insulation, which can no longer really be corrected or are difficult to fix (as you also wrote), apparently because a common basement slab or walls built directly adjacent to each other were used... (whatever).

In the end, besides professional planning, proper execution is also important... we agree on that... which again means that afterwards/or better during the construction phase someone must accompany the correct execution of the proper planning ("my" building acoustician).
Does the prefabricated house manufacturer even go along with that?

If one were mean, they could say to me:
then just build a solid house and that's that.

PS: Regarding compliance with 4100 SST II, the Federal Court of Justice (BGH) has, according to Wikipedia, also ruled on condominiums:

With another fundamental decision, the Federal Court of Justice continues this jurisprudence for condominiums as well (Federal Court of Justice, judgment of June 4, 2009 – VII ZR 54/07). Analogous to the semi-detached house, sound insulation levels II and III of the VDI guideline 4100 or supplement 2 to DIN 4109 can be regarded as generally accepted rules of technology for an apartment that is to meet the usual quality and comfort standards. The court makes it clear that mere reference to DIN 4109 in the service description is not sufficient for its effective agreement as contractually owed sound insulation. Rather, the contractor who wishes to deviate from the usual quality and comfort standards for apartments must additionally adequately inform the purchaser about the consequences of simple sound insulation construction for the later living quality.[7]

I am surprised that I find so little about this otherwise. This is certainly a more frequent topic (like "botched construction").

I'm surprised that I find so little about this elsewhere.

Reason: Hardly anyone thinks about such matters in depth. Furthermore, noise issues rarely occur in the single-family home sector (at most near highways, railway lines, or airports). 99% of houses meet the residents' requirements without making a big fuss.
That's why your run-of-the-mill manufacturer is already annoyed.

Oh, I think the manufacturer reacted quite well. Sure, I was annoying, but after all, it concerns an investment for life.

For me, a certain level of living comfort also includes reasonable sound insulation. The standards and the rulings of the BGH even prescribe this.
In this respect, I continue to try to resolve the alleged contradiction between timber frame construction and sound insulation according to 4100 SST II or even 4100 SST III.

Maybe that’s meticulous, but I find it important. And I want to be able to proudly say afterwards: look here, timber frame can also provide sound insulation. The question is certainly at what price... but let’s get back to the questions above.

No detailed information about the neighboring party wall regarding sound insulation. Fire protection class F 90 B.

Material? I don’t assume that this is supposed to be a timber frame wall as well, more likely Poroton/calcium silicate brick. Anything else would be - unusual.

I’m still looking for someone who has done something like this themselves: optimizing timber frame construction with an external building acoustician (if yes, with whom etc)?

Does the prefab house manufacturer even agree to that?

When I was still working in the industry, I once accompanied a multi-family house and townhouse timber construction, especially in the planning phase. However, that was on the developer’s side in cooperation with the architects; I would seriously doubt that with a run-of-the-mill provider you would get an external specialist involved in the basic layout, production, execution, and detailed planning. You can have the installation accompanied, but then you have only limited possibilities to recognize and influence the misuse that is carried out in the factory.

as apparently a common basement slab or built adjoining

A continuous separation joint is of course the be-all and end-all. From top of foundation to roof membrane.

then just build a solid house and that’s that

Then I’ll ask the other way around: where do you see the advantages of a detached house in timber frame construction?

Then I’ll ask in reverse, where do you see the advantages of a detached house in timber frame construction?

I wouldn’t want to go into that any further here (among other things, the achievement of the KfW40 standard practically from the start).

So you share my concern that an external party can/may intervene without further ado at the prefab house manufacturer.

However, I have come across something else: a certificate for sustainable building from the DGNB. It also contains criteria for sound insulation and the manufacturer is a member of the DGNB. Accordingly, an auditor would have to work in cooperation with the manufacturer. This certificate comes in three levels (gold, silver, bronze... like at the Youth Games).

Has anyone already gathered experience with this?

You can forget DGNB certifications for private single-family homes (it's essentially about sustainability). No gain except additional costs. Very interesting in the commercial sector (office buildings, logistics, etc.).