Make cold attic accessible?

OSB is often used as the top layer. It is also completely harmless from a calculation perspective as long as the vapor barrier (ceiling upper floor) is installed completely sealed and without defects. However, this will probably never be the case, so I would always use something breathable on top.

My contractor and I discussed it because we want to make the attic accessible and reachable by stairs. For the reasons mentioned above, he was also against OSB and in favor of spruce formwork boards. They then nail them onto that.

Hello,

thank you for your opinions. I will screw the roof battens 6x4cm onto the ceiling beams and then attach the [Rauspund] on top. Around the edge, I will leave about 10cm free all around to ensure air circulation.

Now the only question remaining is whether I should treat the boards and battens with some kind of [Lassur], possibly with [Bleueschutz], or if that is not necessary.

Regards, Lars