Metas roof to wood, screw placement, which camp are you in and why?

[marimus]

I could be wrong but I doubt you'd even find a builder over here who would nail a roof.

In QLD at least it's illegal to nail a roof. You must use roofing screws, which are either 50 or 65mm long for metal or timber battens, through the top of every rib along the top and bottom of the sheets, and every third or every second or every rib depending on wind rating, for the other battens.