Cheap insulation. Is there such a thing?
One thing about fiberglass insulation is that it will mold if it gets damp. ......................... Check out Roxul mineral wool insulation. It will not mold ..............................
What you say may be true, but it might leave a false impression
ANY "open" insulation such as bats MUST have at least one vapor barrier..........in this country it's the warm side of the installation, and as Inkjunkie pointed out, ANY opening can allow moisture to condense.
In the case of something "extreme" like a freezer cabinet...........to show how bad this can be...........a very small unsealed opening in the outer skin can allow moister to collect which will freeze, expand, and ruin the cabinet
My point is you MUST have a moisture barrier. I'm not familiar with convention "down there" in the south, so Rob needs to check this. Where it's very humid both indoors and out, an inner / outer barrier might be pretty much required.
Convention up here with these metal skin "pole" (kit) buildings is a completely sealed bat affair that looks sort of like a mattress........the entire bat is sealed into a bag, outer and inner. THAT particular stuff must be very expensive to buy
