Assessment of sound insulation for terraced house

Hello,
we are currently looking into the offer for an end-terrace house (new build, completion expected in 2026). I am somewhat uncertain about the issue of sound insulation between the residential units and would appreciate help in assessing it. The construction specification states:

To protect against sound transmissions from the neighboring house, the increased sound insulation requirements according to Supplement 2 to DIN 4109:1989-11, Table 2, are implemented.

The partition walls within the respective houses are constructed as dry construction [Addition: double-leaf as reinforced concrete or calcium silicate masonry, basement also double-leaf]. A defined sound insulation within the house or requirements according to other guidelines (e.g. VDI 4100) are not agreed upon.

Therefore, no special sound insulation measures are carried out inside the houses.
Accordingly, as an example, the following sound insulation requirement values apply as sound insulation specifications and quality agreements for the following partition components: airborne sound insulation of partition walls between separate residential units: ≥ 55 dB

The sound insulation against outdoor noise meets the requirements of DIN 4109:2018-01. These sound insulation requirements are assigned to a usual comfort and quality standard.

Otherwise, the implementation of the structural sound insulation complies with the requirement values of the publicly legally mandated minimum sound insulation DIN 4109:2018-01. This applies in particular to installation noise, noise from building services, or the main entrance doors

I have tried to read up on the topic and it seems to me that the value of 55 dB is not sufficient, but that DIN 4109 already requires airborne sound insulation of at least 57 dB, and even this is often considered insufficient so that 67 dB should be aimed for and 62 dB can be regarded as state of the art.

I would appreciate an assessment of how well informed I am and how the statements in the construction specification should be evaluated. I also wonder whether DIN 4109 is not mandatory and whether these agreements even have validity? Can an older edition of the standard be agreed? The federal state is Baden-Württemberg, if relevant.

Thank you very much and best regards,
Florian

Hello Florian, unfortunately I cannot contribute anything regarding your question about the DIN standards, but I can only tell you how our house is built and what has proven successful for us.

We have a mid-terrace house and the craftsmen apparently did an excellent job. We don’t hear anything from the neighbors inside the house. Neither footsteps on the stairs (each has two children) nor voices. One family is very musical and you only hear them playing music when you walk past the house. Or rather, the sound penetrates outward through the windows.

House separating walls are double-layered, each 17.5 cm of sand-lime brick with a house separating wall panel in between.

It was important to the architect to have as few or no power outlets as possible on the house separating walls.
The stairs are decoupled on bearings, as was stated in the building description.

Double-layered drywall partitions have been installed.

Toilets and showers are each mirrored on the house separating walls, only the washbasins border inside the children's room walls, so you are not overly disturbed there.

I can only say that I am surprised not to hear anything at all from either neighbor. We did not know what to expect before the purchase. We had actually only heard negative things, but those were all much older houses with sometimes a shared house separating wall.

You basically sit next to each other only on the terrace and in the garden.

What I would do differently today and additionally commission during the planning: terrace separating walls made of sand-lime brick and at least 4 meters deep. This is noise and fire protection combined.

We are also in Baden-Württemberg: terrace roofing without a fire protection wall is only permitted to be 3 m deep. And the roofing must either extend over the entire width of the house or maintain a 50 cm distance to the neighbor on each side.

Ours is therefore 6.10 m wide over the entire width of the house and 3 m deep.

Hey Schrauberlani, thank you very much for your detailed response! Would you mind sending me the part of your construction description relevant to soundproofing? (Also the complete construction description is welcome, I am curious to compare and get a feel for it).

I will send you my email address via PM. (EDIT: Cannot send PMs due to too few posts. You would have to contact me)

Thank you very much!

Hello Florian, yes gladly. I can look for the documents for you, since I also can't write PMs, I would type the text regarding the DIN execution in here. Our house was built 11 years ago. Or attach it here, I have to try what is possible. Best regards Lani