No. It is not fire resistant and you need drywall for fire resistance over the insulation if this is a habitable space.

Hi @User thanks for answering. From what I read online cork is suppose to be fire resistant. Is there maybe some level or official of fire resistance that cork doesn't fulfill?

I would think you would need to have the sheetrock up there and taped in order to install the cork. All the cork I’ve seen would not have the rigidity to be put on a ceiling. Taping the sheetrock so that it doesn’t cause cracks at the joints in the cork.

@mainenell I would first mount some beams on each 20cm and mount the cork on those beams. The issue might be that the surface between the cork and the beams could be not enough for the glue to hold the cork.

Drywall is required. Period. And is far cheaper.