Soundproofing concerns regarding partition walls and controlled residential ventilation

Hello everyone,
we have set our sights on a plot of land on which the associated developer wants to build a semi-detached house for us.

Now I have concerns regarding the choice of walls that the acoustic independence from my neighbor might not be fully guaranteed.
The exterior walls are to be made of about 15 cm thick sand-lime brick. The party wall is to be made of two layers of 15 cm sand-lime brick and a 5 cm thick mineral fiber insulation board. According to the building description, this should achieve sound insulation of 69 dB.

Unfortunately, I can't really imagine what that means. The DIN standard only requires 57 dB, but that is from 1989.
What do you think about this party wall? Is it safe to assume that I will not disturb the neighbor when watching movies? Even if the system is turned up a bit louder? I understand that this question is hard to answer because of many subjective factors. I am more interested in whether this meets today's standards and what experiences you have had with such walls.

What effect can additionally installed gypsum boards on the inside of the party wall have?

Also, the second point:
A central ventilation system with heat recovery will be installed.
Can this lead to sound bridges? If yes, how can this be prevented?

My special focus regarding soundproofing comes from my previous living situation. Here in the old building, there seems to be only some hay and sand between the wooden beams between the floors. You can hear the neighbors having conversations at normal speaking volume and on the phone. And by hearing, I also mean understanding.

With quiet regards
Ricardo

The party wall made of two times 15 cm calcium silicate brick and a 5 cm thick mineral fiber insulation board.

That's great! When concreting the intermediate ceiling, the gap between the semi-detached houses must be covered. Falling concrete could create a sound bridge. Otherwise, in my opinion, everything is perfect, you don't need to worry.

A central ventilation system with heat recovery will be installed. Can this cause sound bridges?

Yes and no. Normally not between the semi-detached houses, if the above-mentioned applies or if each half of the house gets its own controlled residential ventilation. Everything else then depends on the planning and execution of the controlled residential ventilation.

Hello Ricardo,

The exterior walls are to be made of approximately 15 cm thick sand-lime brick. The party wall between the houses is made of two layers of 15 cm sand-lime brick and a 5 cm thick mineral fiber insulation board. According to the building description, this should achieve a sound insulation of 69 dB.

It decisively depends on how wide the gap between the two semi-detached houses is. In the described case, would it have to be >5 cm? With or without a basement?

I can't imagine what that means. The DIN standard only requires 57 dB anyway, but it is from 1989 after all.

This DIN standard is still valid. However, you should internalize that the application of standards is basically voluntary. Standards become legally binding if laws or regulations, such as EU directives, refer to them. Additionally, contracting parties can also make the application of standards binding through agreements.

What do you think of this partition wall? Can I assume that I will not disturb the neighbor when watching movies? Even if the system is set a bit louder?

That depends less on the thickness of the party or building partition wall and more on the size of the separating joint and its careful construction! Through your question, I also learned again where (hidden) savings can be made; we generally build the party wall with 24 cm KS, plus mineral wool + air gap.

A central ventilation system with heat recovery is installed. Can sound bridges occur here? If yes, how can they be prevented?

No, why? Each semi-detached house receives its own ventilation system, right?

Rhenish regards

3 dB noise reduction corresponds to a "perceived" halving of the noise.
So if you go from 57 to 69, you have a 12 dB difference - that is extremely much!

Hello Bieber,

That's great! When concreting the intermediate ceiling, the gap between the semi-detached houses must be covered. Falling concrete could create a sound bridge. Otherwise, in my opinion, everything is top, you don't need to worry.

That sounds good so far. Isn't there a 5 cm mineral fiber insulation board flush between the two partition walls? So that nothing could fall in there.

Hello building expert!

It crucially depends on how big the gap between the semi-detached houses is. In the described case, would it have to be >5 cm? With basement or without?

It will be built with a basement. I can't tell from my currently available documents how big the gap is. Does the description of the partition wall also apply to the basement?
Are semi-detached houses regularly connected somewhere, aside from the roof truss?

This depends less on the thickness of the party or building partition wall, but on the size of the separating joint and its careful design! Although your question also taught me where savings can (secretly) be made again; we fundamentally build the party wall with 24 cm KS twice, plus mineral wool + air gap.

You build the partition wall from 2 times 24 cm calcium silicate blocks plus mineral wool. So about 18 cm thicker than planned here. Considering the stone alone, roughly the equivalent of one of my walls additionally.
Should I be worried now?

Regarding the ventilation system:
This was about sound transmission within the house. Each house will get its own system.

Hello Wastl,

A 3 dB sound reduction corresponds to a "perceived" halving of the sound.
So if you have from 57 to 69, you have a 12 dB difference - that is extremely much!

Yes, that's how I calculated it myself. Still, I have no exact idea of 69 dB and thought that house builders in 1989 simply didn’t have such high demands or expectations and therefore assumed 57 dB.

Actually, your answers have put me in a positive mood. Except for the hint from the building expert that apparently 24 cm KS is used twice...

Should I have an expert pay attention during construction to ensure that the separation of the semi-detached houses is done properly? Over what period can errors occur here? If this period is too long, it will probably be overly expensive to have an expert supervise this issue. But this problem is a sensitive topic for me. I would even say the most important.

And does anyone have experience with the additional sound insulation effect of gypsum boards on the partition wall?

Best regards and many thanks in advance
Ricardo

What you need to pay attention to / should pay attention to: Build 2 completely separate basements. That means 2 white tanks, or whatever. No continuous base slab! Otherwise, you create such a large sound bridge that no matter what you do upstairs, you will always hear the neighbors.