Sound-transmitting multi-family house, how to renovate the intermediate ceiling?

The problem is that you don’t know 100% what the cause is and how dramatic the situation really is. Currently, we only know that previous tenants found it too bothersome. Then one can suspect that it is indeed a problem.

But you can only suspect it.

Well. The assumption is obvious that because the floorboards are firmly screwed to the wooden beams, the sound penetrates unhindered there and is radiated downwards. Possibly, relief is already created if you lay a floating floor on the floorboards that has a suitable soundproofing mat between the floorboard and the floor covering. Whether that is really a good solution, I don’t know.

Insulating under the ceiling to reduce the sound I consider a solution but rather a very bad solution. Why? Once the sound is in the ceiling from above, it also radiates further through the walls. Therefore, I consider it most sensible to prevent the sound from entering the ceiling/floor in the first place.

Difficult subject. I would definitely not pour screed without a structural engineer. As you said, the house is already somewhat older. If you add too much mass to the ceilings/floors, the thing will collapse, and such screed is really heavy!!!

If I were you, I would wait for now. Maybe it can be found out what the cause is.

Maybe you can lay about 1 m² of a good soundproofing mat on the floorboards and put a board/floor covering on it. Then have someone jump on it and do a hearing comparison underneath. If it helps, I would then probably lay the soundproofing mat on the floorboards and a floating floor on top of that.

But these are all just assumptions. Who knows...

€: If you want to keep the floorboards and use them as flooring, it might also help to unscrew them and decouple them under all beams/supports on which the floorboards rest with sound mats/strips. Also, add a perimeter insulation strip as well.

Thank you very much, I also see decoupling the first layer as well as the edges from the wall as the most sensible application. Now we have the following comments that oppose each other:

Not floating, by any chance?

lay the soundproof mat on the floorboards and a floating floor on top of it.

Laminate on the floorboards is usually laid floating.
However, decoupling the floorboards from the joists and the walls, how do you then reattach the floorboards?
Every screw you put in creates a connection to the joist again, and screws made of rubber do not exist yet, do they? ;)

If only the screw remains as a sound transmitter, I think it will be done (provided that this is actually/was the problem)

What I find strange is whether your floorboards are anchored in the wall or the wall is placed on the floorboards or how should one imagine that?

I haven't seen that even in older houses. They all end about ~1cm before the wall, if only because of the expansion joint

I have several (older) houses and all the floorboards have so far been recessed 1-2cm into the wall. But when I am at the house next time, I will check it, I think it will be the same here...Thank you for all your practical suggestions, they have helped me a lot. I can get back to you then, but it will take a little while.

and how is it with your other old houses in terms of sound?

What have you done there or how is the ceiling construction there?

Just the usual boom boom when you walk, but when you talk you really don’t hear much. So nothing has ever been done here either, or I have never dealt with the subject for that reason. Ceiling structure: floorboards on beams, clay plaster on wooden slats, cavity, thin wooden laths as a sub-ceiling and reeds with plaster hanging on them. I think it’s like that almost everywhere in old houses.

So if you are already removing the floorboards to decouple from the beams, you might as well fill the cavities with insulating wool and be done... I think that would be a generally feasible and relatively sufficient solution :rolleyes:

Everything else will probably really bring little result, or be too complicated & expensive...