Hi everyone,
We are living in a small unit which has a ceiling made of tounge-and-groove board. I don't know the materials. It's around 20mm in thickness. I'm looking into insulating the ceiling. Is it worth it? How would we do it? Do we just put ceiling insulation batt on top of the ceiling or is there another way we can do this?
Photo from our unit looking up to the ceiling:

This is on the attic:

The tounge-&-groove board.

Thank you!