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 vault underneath is exposed and then in the

there is a clear difference between the ground floor and the basement and between the ground floor and the first floor

Since quite a few answers were wrong, here is my opinion. Thermal insulation between heated living spaces is not necessary. Any kind of foil is not needed either. Paper is sufficient for dust protection. Soundproofing, both structure-borne and airborne sound, can only be reduced by mass, not by lightweight materials like glass wool or styrofoam. Depending on what the construction debris consists of and how it is executed, you can leave it in or remove it from above. If the upper floorboards are to be replaced, they can be replaced with new floorboards or OSB (structurally better). Removing the reed matting is a lot of work and dirt, but it doesn’t affect the new window on the ground floor.

there is a clear difference between the ground floor and the basement and between the ground floor and the first floor

Yes, and now?^^ I explicitly wrote that this is what WE are planning. Not that I recommend it in this case.

I am currently dealing with exactly the same issue. The plan was also initially to remove the old filling, put in new filling, and OSB on top.

When I described this at the hardware store and showed photos, I was immediately advised to leave the old filling in place ([Bauschutt usw.], relatively heavy material) and fill up flush with heavy filling from the hardware store. First remove the old filling, insert a leak protection, then put the old + new filling on top. Finally, lay 20 mm floating dry screed elements (glued and screwed together). Optionally, an 8mm wood fiber mat under the elements, or at least insulation strips on the wooden beams.

Main arguments against OSB / for dry screed: higher sound insulation due to more mass, no screwing to the wooden beams and thus decoupling of the floor. I am willing to pay the three euros extra per sqm for that.

Dry screed can definitely be processed very easily. The panels are quite heavy, but easy to cut and lay.

I heard that too - I'm just skeptical whether the recommended 20 mm thickness is enough.