Curious but had to ask - Fiberglass Exterior Roof

Those of you that have skinned your tear with the White Fiberglass - (On the Roof - Exterior.. how thick of ply did you use underneath?
I was thinking of 3mm since my Fiberglass Sheeting is 1.8 mm in thickness but actually does it need to be at that thickness? I do have the 1.5 mm ply sheeting left...
Maybe Paul from Down Under can chime in...
Classic Finn
I was thinking of 3mm since my Fiberglass Sheeting is 1.8 mm in thickness but actually does it need to be at that thickness? I do have the 1.5 mm ply sheeting left...
Maybe Paul from Down Under can chime in...

Classic Finn
