Is sound insulation according to DIN 4109-1 sufficient for a mid-terrace house?

If I guess correctly, you will have much bigger concerns with other points than with the sound insulation standard.

There might be something to that. The offer I have for the mid-terrace house is 500k with a basement (120 sqm, 5 rooms) including ancillary construction costs (fixed price). At first glance, including a flyover over the balance sheet / profit and loss statement, the developer looked solid without further research when I came across the sound insulation issue. It just can't be that you save on sound insulation and in the end hear neighbors like in GDR panel buildings.. *slightly exaggerated formulation

Our acquaintances had contractually agreed on enhanced soundproofing; after completion, it turned out that the builder simply constructed "as usual" regardless of the contract and only met the minimum requirements according to DIN4109. This was determined by an expert. They told us this after we had visited and had heard both the children running on the wooden staircase, as well as the piano playing and a (admittedly extreme) coughing fit of the grandpa from the neighboring house. However, the structure-borne noise is reportedly worse for them than airborne noise. As soon as there is normal everyday life with children in our acquaintances' house, they hear nothing except for neighbors occasionally walking on the stairs; but when it is quiet at their place and there is normal life at the neighbors' house, it becomes more noticeable and really annoys them. The neighbors, however, are not bothered by the noises from our acquaintances. I think it really depends on how sensitive you are and how important the topic is to you.

The offer I have for the terraced house in the middle is 500k with a basement (120 sqm, 5 rooms) including additional construction costs (fixed price).

Just tell me the provider. Although I have the same name at gmx (de) as here, being a developer is not something that would make ladies blush, so you can actually name it here openly.

It can't be that they save on soundproofing and in the end you hear the neighbors’ voices like in an East German panel building.

The panel buildings in the West had lower standards compared to the world level, just to mention in passing. And of course, it can be the case that in the service of prices desired by the buyers, standards according to norms are considered sufficient. I would like to read more closely about what the "separation joint panels" are supposed to mean. To me, that sounds like sandwich, technically rather the opposite of what the advertising word suggests.

I think it really depends on how sensitive you are and how important the topic is to you.

Good point, and the external noises from the neighbors would really annoy us (my wife and me) later on and possibly the neighbors as well..

DIN 4109-1

yes, it is the minimum requirement in residential construction: This includes, for example

[*]living rooms (including entrance halls, eat-in kitchens), [*]bedrooms (including overnight rooms in accommodation facilities), [*]bed rooms in hospitals and sanatoriums, [*]classrooms in schools, universities, and similar institutions, [*]office rooms, [*]practice rooms, meeting rooms, and similar work rooms.

It is usually assumed that rooms intended for permanent occupancy must have windows. Room combinations such as “eat-in kitchens” or “bath en suite” (bedroom with bathroom facilities) are generally considered living spaces, while corridors, traffic areas, or ancillary rooms are generally not included.

The purpose of the minimum sound insulation is to protect people in living spaces from unreasonable disturbances caused by sound transmission, to avoid endangering health. The requirements were most recently expanded to cover “satisfactory night rest, leisure, and working conditions.” In addition, confidentiality during normal speech is regarded as a protection goal. Based on a background noise level of LAF,eq = 25 dB, the above goals are achieved according to the standard for rooms requiring protection, for example in apartments, dormitories, hotels, and hospitals. It cannot be expected, however, that noises from outside or adjacent rooms will no longer be perceived or will not be perceived as disturbing, even if the requirements are met. Source: Baunetz-Wissen

what even the developer mentions in the construction description?

I assume that you misread something. Or was it a parody of his construction service description? No one disparages their house construction if they have to live off it. No company builds negligently below the minimum requirements and no company calls a DIN that describes the minimum standard (and which is sufficient in most cases) insufficient. That is simply all illogical.

I assume that you misread something. Or was it a parody of his construction performance description? No one speaks ill of their house construction if they have to make a living from it. No company builds negligently below the minimum requirements, and no company calls a DIN standard, which describes the minimum standard (and in most cases is sufficient), inadequate. That is simply all illogical.

The construction description states that the DIN 4109-1 requirements are met, but not the standard of increased sound insulation for a mid-terrace house, which is usually expected for a mid-terrace house. That is written in the construction description – no joke. That surprised me a lot, as the provider thereby speaks badly of his product or is legally securing himself.