Originally Posted by o_q
I don't quite understand this bit. Are you saying that some people say that this method of insulation is improper? Or are you saying that improper insulation in general will cause mold and mildew?
I was also wondering how hard it is to remove this sort of insulation.
It's the improper installation (not insulation) that creates the problem.
What most folks do is spray or roll contact cement on the both surfaces then press on the insulation. As long as there are no gaps between the roof and the foil, there's no place for the mildew or mold to really get started. Basically as long as you do a proper prep of the surfaces (no big lumps and bumps on the coachroof), it works great.
I've never tried to remove it but I have the feeling it wouldn't go well. Thin foil and grabby glue usually mean a lot of swearing while wielding a putty knife (or possibly gas and matches from the dockside depending on how long the swearing has gone on