Construction of low-slope roof

[daer01]

Hey!
I'm working on the garage and was thinking about what to do with the inside of the roof. This concerns a low-slope (1 degree) garage roof with a 3-layer covering. The surface layer is according to T-emballage vapor-tight (of course) and therefore I can't have plastic on the inside of the roof. What should I do then? Vapor barrier or should I simply skip putting anything up and just install the battens?
The roof structure looks as follows, from the inside out:
Gypsum - battens - 270mm insulation - 45mm air gap - tongue and groove - roof covering

So... layer between battens and insulation or?
Thanks in advance

 

[Rickard.]

You should have a vapor barrier between the insulation and the paneling, as you have ventilation under the raw wood, that is absolutely correct.

 

[daer01]

Leaning a bit in that direction too since the air gap removes any moisture. I forgot to mention that I have a wind barrier that creates the air gap, but it is diffusion-open so it shouldn't matter, right?

 

[Rickard.]

It probably just makes it even a little more important to have a vapor-tight seal on the inside.

 

[daer01]

Then I'll use diff.plast on the ceiling since the garage is supposed to be heated, that's not something that changes the situation I guess?

 

[Rickard.]

No, go ahead