ᐅ New construction extremely sound-transmissive or sensitive to noise

Hello everyone!
We have been living in our newly built 145m2 (1,560 sq ft) house since Easter.
The exterior walls are made of aerated concrete with a brick veneer. The interior walls are made of calcium silicate bricks.

Yesterday, something happened that really surprised me.

We have a walk-in closet on the upper floor. My wife was hanging clothes on metal hangers there.
At the same time, I was sitting on the toilet on the ground floor. I could clearly hear her sliding the hangers over the metal rods from there.

Overall, the entire new house feels extremely noisy! You can hear every little sound, even from the bathrooms...

Can anyone explain this to me?

Did you have an inspector present? Did they check the installation of the floating screed? What did you do with the perimeter insulation strips of the screed?

No, an appraiser was not present. As far as I know, the edge strip was cut off during the installation of the flooring.

I’m really curious to hear your thoughts on this... We also have a serious noise issue in our "new build" apartment from 2018. We can hear footsteps or heavy walking from upstairs extremely clearly. We even hear light switches being clicked. Depending on the volume, we can hear people talking. The most surprising thing is that we can hear their bathtub—or whatever they are doing in it—from every corner of our apartment. For example, splashing sounds as if water is dripping right above my head, or you can even hear when someone is just moving around in the bathtub.

So, as I said, I’m looking forward to your opinions here... maybe I should start a new topic myself.

I always suspect poorly insulated openings in cases like this. I once lived in a rental apartment from the 1950s where there were shafts that probably ran from top to bottom without any insulation. I could hear my neighbors peeing while lying in bed in the bedroom.

Sound inside a house spreads either as structure-borne noise or airborne noise. The former can be controlled with good construction quality by ensuring that structure-borne noise does not transfer from the floor to the walls and vice versa. Building components are decoupled. Hanging clothes does not produce structure-borne noise (too little energy, too high frequency). In this case, open doors and hard reflective surfaces (floor, walls, ceilings…) can facilitate sound transmission. Newly occupied houses often feel somewhat "bare" and transmit mid and high frequencies easily from room to room. It also seems that your entrance area is tiled, which likely causes noticeable echo and clatter in that space. If, in addition, the hanging rod for clothes hangers in the dressing room is attached directly to the wall, loud clattering of hangers is to be expected, even if there is no material defect.

Make sure you avoid hard surfaces facing each other. Sound can either be dampened or diffused. That will help a lot.

Acoustic elements on the ceiling make a room feel cozy—for example, from Ligno Trend.

Unfortunately, acoustic comfort is often overlooked during the planning stage.