owed soundproofing terraced house new build

Wait a minute, you're already two steps ahead.

I had assumed that sufficient soundproofing would be achieved. How high it needed to be was not clear to me at the time of purchase, and whether such a house would be built as a single-layer or double-layer structure was also not clear to me. A bit naive of me, you can blame me for that, but oh well. I had the purchase contract reviewed by a construction law attorney, and he had no objections to the wording.

My building inspector then brought the issue of the single-layer wall to my attention. Subsequently, we, or rather he, commissioned the soundproofing report. I neither expected nor demanded a specific value, but only wanted to see the calculation because the planners had made several serious but still correctable mistakes. The result was that we were told by the contractor (this is not the developer but a general contractor hired by the developer, so we do not have a contractual relationship with him per se) that errors had been made in the soundproofing calculation and that he had commissioned a new soundproofing report. Today he told me that they had also checked with another expert and that the required soundproofing of 62 dB would be achieved through the subsidiary layer. The fact that a soundproofing of 62 dB is owed comes from the contractor who is implementing the developer’s plans and not from me. Accordingly, I do not expect the position regarding the apartment building to be invoked.

Apart from that, I bought a house from the developer. If he wants to install a subsidiary layer there, that is certainly very annoying for me, but of course, it is his right.

What is questionable for me, therefore, is rather which value must be achieved and whether this can be reached by the measures. I do not have legal expense insurance for this case, so if I want to escalate it, I should be relatively sure.

What exactly was unclear to you here that you had not bought a "house" in the usual sense?

Nothing about that was unclear to me. How do you come to that? I know the construct, I have been living with it for years. The ruling (I also found others) states that it is about the shape of the building and not about the declaration of division.

So that was a planning error by the architect, the developer wanted at least 62 dB, but did not get it delivered.

I read that differently as well. The architect was commissioned to plan "two rows of terraced houses with five terraced houses each" which the developer sold "as terraced houses in the form of condominium ownership." Identical construct as with us. The architect then interpreted these "terraced houses in the form of condominium ownership" as multi-family houses (vertically) and based the requirements on those for a multi-family house. This was not correct, since it is irrelevant whether they are "terraced houses on their own land or condominium ownership on undivided land."

I had assumed that sufficient sound insulation would be achieved. How high it had to be was not clear to me at the time of purchase and whether such a house is built as single-shell or double-shell was also not clear to me. A bit naive of me, you can reproach me for that, but oh well. I had the purchase contract checked by a construction law attorney and he had no objections to the wording.

Your contract with the developer states the following: "The minimum requirements according to DIN 4109:2018 for building acoustics (sound insulation in interior spaces) are met."

So if the topic of sound insulation concerned you that much, you should have taken a look at this DIN before purchasing or even better asked an expert for advice. Your construction law attorney surely explicitly made you aware that you are buying a vertically separated condominium, right?

"My building inspector then made me aware of the issue of the single-shell wall."

but apparently only AFTER purchase! By then, the damage was done....

That a sound insulation of 62dB is owed comes from the contractor who implements the developer’s plans and not from me. Accordingly, I do not assume that reference should be made to the position of the multi-family house

But as you rightly recognized, you are only the buyer. How the internal relationship concerning contractually required services between the general contractor and the developer looks like or who owes what to whom is not your concern. The above judgment can possibly (!) only be applied between these two parties. Interesting for you, however, is only the purchase contract between you and the developer—and there you have clearly purchased a condominium and thus, as agreed in the notary contract, only the minimum level of a multi-family house according to DIN must be delivered to you. If the general contractor should offer you more out of goodwill: nice, but just goodwill, which in the end will cost you a good square meter of space—especially with the relatively small width, due to which the already tight rooms will be even more cramped...

I read that differently as well. The architect was commissioned to plan "two rows of terraced houses with five terraced houses each," which the developer sold "as 'terraced houses in the form of condominium ownership'." Identical construction as with us

No, because you did not buy a "terraced house in the form of condominium ownership" but rather a "apartment (with terraced house character)." Do you notice the difference? Primarily, you were sold an "apartment," i.e., a condominium. The "character" is initially irrelevant because it is not legally enforceable;), especially since it is put in parentheses, more as a popular explanation. And as already mentioned, the internal relationship between the general contractor and the developer can and must be irrelevant to you. You bought an "apartment" for money; you received an "apartment" for money. Contract fulfilled. And the sound insulation as per the contract according to DIN standards, which then applies to an "apartment." "Character" is, as always in life, nice, but you cannot claim money or anything else for it. Is that understandable?

I am fully aware of what I have purchased and what contractual relationship I have with whom. However, based on everything I have read so far, the soundproofing requirements for a terraced or semi-detached house apply to such a terraced or semi-detached house, completely independent of whether it is a legally divided plot or a [WEG] structure. Where you get the certainty that something else should apply is unclear to me. No one is acting out of goodwill here either; I have not even made any demands. I have only asked for the soundproofing certificate, which resulted in the general contractor informing me that their soundproofing report after construction was incorrect and, according to the new report, the building is to be constructed differently than planned.

From everything I've read so far, the soundproofing requirements for a terraced or semi-detached house apply to a terraced or semi-detached house, completely independent of whether it is a legally divided plot or a WEG structure. I don't understand where you get the certainty that something else should apply.

You yourself mentioned that you had purchased a "flat (with terraced house character)" according to the notarized purchase contract. Do you have that now or not? A "flat"!

Furthermore, you surely received a floor plan in advance and probably also included it in the notarized contract. Did it show a single-layer or double-layer wall?! Probably the former. If you interpret "terraced house" in the narrower sense, i.e., in your favor (which a judge would initially also have to see that way, which is not guaranteed), you should have noticed by then that you do not even have such a thing stated in the contract. In other words, that you are instead only buying a share in a multi-family house, which could be described as a terraced house in the broader sense, i.e., a "flat (with terraced house character)". Which the general contractor had exactly written into the contract.

You both then implicitly signed your Servus under that. The notary can confirm it. End of story!