Insulation of intermediate ceiling

Hello,

I have a question about the insulation of my intermediate ceiling, as I'm not entirely sure if everything is correct with the vapor membrane, etc.

It is a beam ceiling, both sides of the ceiling are occupied and heated.
The structure is as follows from top to bottom, as shown in the drawing:

- Chipboard installation panel 38mm
- 1cm air cushion
- 5cm loose fill in anti-dust fleece
- Chipboard installation panel 19mm
- 5x3 roof batten as support
- 120mm Isover Ultimate wood construction panel 035
- Vapor membrane/vapor barrier
- Battens
- Wooden ceiling/drywall ceiling

Now to my question...

I would install a vapor membrane foil in the regular living rooms, even though I know it is actually not necessary, since both sides are heated. But I have concerns that mineral wool dust might come through the ceiling at some point. So it is installed more as a health aspect.

Do I need a vapor membrane foil or a vapor barrier above the bathroom? The ceiling in the bathroom will be made of impregnated drywall panels.

Thanks and best regards,
Christoph

You can install a vapor retarder with a variable moisture permeability under the DeBa, sd-value between 0.03-5, which allows drying back, with joints carefully sealed. The vapor retarder must also be tightly bonded to the rising walls with the manufacturer's system-approved cartridge adhesive and then plastered air-tight. Convection of warm, moist air into the ceiling construction, especially in the bathroom, must be absolutely avoided.

Thank you for the answer! Does that mean an Isover Vario climate membrane would be the right choice? I actually wanted to write vapor membrane and vapor barrier before, sorry...

Thank you and regards, Christoph