The roof itself is felt (membrane) & battened, so I think that’s fine? I am considering putting a wood burner in this summer house though, so I think that could potentially introduce vapour issues — or is that incorrect? Thanks

Good idea, thanks!

Unfortunately the insulation is the full depth of the truss. I guess I could put battens over the truss to basically make a raised platform for the attic floor so that air can then get underneath and to the kingspan, but is it still fine with the plasterboard tight against it underneath? Thanks a lot for your response by the way, much appreciated

So plasterboarding tightly underneath and putting floorboards direct on top should be fine? And I’m from the UK, I tried the UK DIY sub but only received some vaguely related replies and not what I was looking for so I thought I’d check this sub. Lots of rain where I’m from, all year through ha.

Thanks for the reply!