Renovate wooden beam ceiling and construction

Oh, let me tell you what we are planning. We will remove the slag on the ground floor until the underlying vault is exposed and then reconstruct it with a dry screed system. With dry screed filling, insulation, dry screed (I don’t remember the exact order right now). But this is mainly for thermal insulation. Due to the high effort, we have decided to keep the original structures of the ceilings.

Oh, I'll tell you what we plan to do. We will remove the slag on the ground floor until the vault underneath is exposed, and then rebuild it using the dry screed system.

On the ground floor to the basement, thermal insulation and possibly moisture protection are needed, but no sound insulation. Between the ground floor and the top floor, if both are heated, no thermal insulation is needed, only sound insulation.

Yes, exactly that is what I wrote. It is used for thermal insulation. But the structure is still similar, in the ceilings just with more soundproofing but without insulation.

Between the ground floor and the upper floor, no insulation is required. Depending on the use of the rooms, however, different levels of good soundproofing are needed: structure-borne sound from footsteps and noises in the upper floor are only reduced by mass. Glass wool helps little here. The old loose fillings often have the disadvantage of lacking protection against trickling and rodents. Depending on how much waste was installed at that time, the house smells more or less. You can therefore leave everything, remove everything, or only the [above the secondary floor]. From above or below

Hello everyone,
I’m joining the discussion here and not opening a new topic separately.

We are facing a similar task.
As part of a renovation, the sound insulation between the ground floor and the upper floor is to be improved (wood beam ceiling).
Today, the structure is as follows: beams, 23mm plank layer, vapor barrier, 19mm chipboard, dry screed (55mm, of which 30mm is impact sound insulation (styrofoam)). The ceiling on the ground floor is fastened to the beams with battens.
Between the rafters there is glass wool – however, the rafters are by far not completely filled.

Today, conversations from the ground floor are indeed noticeable on the upper floor. You don’t understand every word, but of course that is still disturbing.

As part of the renovation, underfloor heating is also to be installed on the upper floor. And if the structural engineer gives the OK, we do not want to use dry screed but rather wet screed in order to get more mass. Due to the underfloor heating, there must be thermal insulation toward the ground floor (according to my understanding). Thus, the floor structure changes somewhat...

My question is: What to do with the glass wool in the rafters?
I have read in various articles that it would be sensible to get more mass into the rafters to reduce structure-borne sound. For this, the entire floor would have to be opened (from above) and an insertion level installed and filled with loose fill or lightweight concrete.
Simpler would of course be blown-in insulation, e.g., mineral wool.

What do you consider sensible here?
Is the mass possibly gained through the wet screed sufficient to achieve better insulation concerning structure-borne sound?
Or should the effort be made to install an insertion floor between the beams and insert loose fill etc.?

Regards
Christian

We chose a very similar structure, with cement screed on Styrofoam on OSB boards on beams, which are filled with stone wool in the space between. Below that are battens, counter battens, and plasterboard panels. From the upper floor you can hear every step, it is not suitable for sensitive ears. Our architect told me that only mass helps against noise. In another forum (it is about half-timbered houses) there is the standard advice to use pavement slabs as filler in the beam layer. If you care about soundproofing, I would definitely spend some time filling the beam space with something heavy. The wool doesn’t help.