owed soundproofing terraced house new build

Here is another judgment from the OLG Munich (28 U 1921/05) regarding a semi-detached house divided under [WEG]:

“Even though it was legally condominium ownership, the OLG said, the developer should have complied with the standards applicable to semi-detached houses in terms of sound insulation. This is a property with several floors, a separate basement, its own hot water and heating supply, its own staircase, its own front door, and its own house number. Such properties are to be classified not as an apartment but as a semi-detached house and must be insulated differently according to the rules of technology.”

How else could this be interpreted???

Or here again OLG Munich, decision of 03.02.1998 - 9 U 3922/97:


1. If terraced houses are built without real division of the property in the legal form of condominium ownership, the sound insulation does not comply with the requirements for multi-storey buildings with apartments, but rather with those for party walls in terraced houses.

2. Double-shell party walls are recognized state of the art in terraced houses even if they are not explicitly required by DIN 4109.

As far as I know, an appellate court is not required to follow what another appellate court decides. (No legal advice and no idea whether it is usually the case that they come to similar conclusions or not) The question then is whether one would want to argue about that.

Therefore, the question is what your desired solution actually is. I hardly believe they will demolish the house/apartment again and rebuild it with a double shell. (I just assume, from a structural perspective, it is difficult to achieve that retroactively) Maybe talk to an expert about what they say regarding the alternative solution or whether they would see any other measures?

I would also be interested in the sound insulation certificate. If it is available, you must definitely post it here (of course, redact addresses and names). I also frequently prepare sound insulation certificates for apartment buildings and semi-detached/terraced houses, but I have never seen a normal single-layer partition wall between apartments with an R`w value of over 60 dB.

Of course, no one wants to argue about this, and before that starts, I need to get completely different legal advice than what a forum could provide. Ultimately, I just wanted to point out that it is simply not the case that one can say "It is an apartment divided according to the WEG, so the sound insulation requirements from multi-story residential buildings apply."

What do I want to achieve?
- The best possible sound insulation with the current construction method, provided that the costs (loss of space, redesigns in the kitchen area) are matched by sufficient benefits (better sound insulation). Here, has expressed doubts. I will know more precisely at the earliest once the sound insulation certificate is available.
- If there is a defect and the owed sound insulation is not achieved even with these additional measures, I want to be compensated for it. This potentially leads to reduced living comfort, or at least a depreciation in value.

It really is a strange construct. The developer, my contract partner, has little knowledge about construction and relies on an architectural firm and a structural engineering firm, both of which show a really poor performance. He commissions the general contractor (GU), with whom I settle everything despite not having a contract relationship, negotiate additional costs or refunds, meet with the craftsmen, etc. He functions well, delivers good-quality work, and has already performed additional work multiple times to compensate for the planners' mistakes. So far, I have only had contact with the GU regarding the sound issue, and he also commissioned the additional expert reports.

As soon as I receive the expert report, I will of course share it here.

An update from me: I have not yet received a joint appointment with the developer, but to avoid embarrassing myself with my legal opinion, I have contacted my lawyer from the contract review again.

He comes to the following assessment:
- Sound insulation for terraced houses is owed; the values for apartment buildings do not apply due to the construction method.
- The minimum sound insulation according to DIN 4109 does not apply. The Higher Regional Court Karlsruhe has determined that the minimum values were already outdated in 1989. To achieve a usual quality and comfort standard, increased sound insulation is required (e.g., BGH VII ZR 45/06 and BGH VII ZR 54/07). Also interesting in this regard is the reasoning:
"Rather, the reference to DIN 4109 is to be understood in good faith as a promise of sound insulation corresponding to this standard, insofar as DIN 4109 is recognized as state of the art. If a contractor wants to deviate from the recognized rules of technology, the buyer may expect corresponding clarification beyond the reference to DIN 4109, which clearly shows that the minimum requirements of DIN 4109 no longer correspond to the recognized rules of technology, so the buyer receives sound insulation that is significantly below the requirements he may expect for his apartment."

As a benchmark, for example, DIN 4109 Supplement 2 or (since withdrawn) DIN 4109-5 with 67dB each should be used.

He also told me, of course, that the developer is quite free in how he now wants to achieve this, provided it is achievable.