condensation under colorbond - blanket options?

I'm looking at the options for blanket type insulation under a roof (cool/cold climate so freezing tin/warmer air is the issue). The current roof extends past the back wall of our house over a veranda. The house section is fully insulated with batts and reflective foil laminate, but the outside area doesn't have any insulation so for 1/2 the year this area gathers condensation at night and drips onto the veranda deck area all morning.

I've been going to lift the back section of roof and install 55mm anticon insulation blanket extending over the deck area, but I've also been told to look at the air/foam/... cell type blankets. My question is will these perform as well as glass batt foil blankets in stopping condensation forming in this situation?

some options:
http://www.protherm.com.au/index.php...d=11&Itemid=41
http://www.air-cell.com.au/pages/retroshield.htm

I'm guessing that glass blanket would be best (and I know it will work) as the objective is to remove air-flow and air pockets underneath the colorbond, and having the glass blanket pressed against it achieves this. The twin laminates I've seen are fairly flat and wouldn't press into the corrugations like glass blanket will (especially between battens). It seems that these won't stop condensation forming and are reliant upon runoff being directed towards the gutter?

Cheers,
Eastie


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