Replace stretched felt ceiling with gypsum ceiling. How to frame?

[HantverksMannen]

Hello. We are going to replace the stretched cardboard ceiling and install gypsum. The house is from 1956. The ceiling is an interior ceiling on the middle floor. There is tongue and groove in the ceiling. We will also lower the ceiling to accommodate spotlights that require 36 mm. How should we frame this? Can we screw 45x95 directly into the tongue and groove and attach the gypsum to it? I will level it with plastic shims between the frame and the tongue and groove.

 

[ricebridge]

It is perfectly fine to screw into råspont.

 

[HantverksMannen]

Upon further reflection, 28x95 should be enough because the plasterboard is 13 mm thick, so I get 41 mm, and then the spotlights will fit without lowering the ceiling more than necessary.
Should there just be air between the plasterboard and the raw wood, or should insulation, moisture barrier, or something else be added while you're at it?

 

[surris]

On second thought, 28x95 should be enough because the plasterboard is 13 mm thick, so that gives me 41 mm, and the spotlights will fit without lowering the ceiling more than necessary.
Should there just be air between the plasterboard and the raw planks, or should insulation, moisture barrier, or something else be added while we're at it?

No insulation needed unless you want to insulate due to noise from the upper floor. No plastic.