I am currently erecting my trusses and have been thinking more carefully about the insulation stage. Just a quick question. I have seen roofing insulation put directly under the roofing tin (I'm having tin) and I've seen it put directly over the ceiling between the rafters. (And I've also seen it done in both locations under the one roof.)
Is one better than the other? Is under the tin more effective at keeping heat out and on the ceiling better to keep heat in?
I am building a container house and will be having fibreglass batts between the ceiling joists under gyprock cover. But as I have more issues with cold than heat down here in the Southern Tablelands I want an extra layer of roof insulation. So - on the roof or under the tin?