Air gap above interior masonry

Hi,

we have just discovered that we have an air gap of about 10 cm between the interior masonry and the roof battens on the upper floor. I have read online that some people fill this gap themselves with insulation wool to achieve better sound insulation.

Has anyone here done this as well? Does it work, is it effective? If yes, does it need to be protected with a foil (since it is beneath the vapor barrier/retarder)?

You mean between the rafters and the masonry, right? Because the battens have to be on top of that, otherwise you can't really form a proper ceiling.

We have that too, sound insulation probably won't be improved much – the door is the first weak point ;)

We also glued the vapor barrier room by room – which of course also provides a certain amount of sound insulation.

Unfortunately, we don't live there yet to give a practical report.

Yes, exactly.
Between the wall and the counter battens :)

But the gap leads directly into the next room, just 2 drywall sheets and a short distance in between.

Above the doors there are 2 doors plus a longer distance.

Can you stuff something in there - you don't need to tape anything else because it doesn't condense there. But I still doubt that you will notice anything. However, we planned it so that no bedroom borders another, so the issue is definitely rather minor for us - if it even exists at all.

So, the drywall installers stuffed something in there when sheathing with the drywall panels anyway, so I would have only done unnecessary work :D

At least with the straight walls, with the slanted ones they have nothing in between.