Although there are many types and brands of insulations,
rigid insulation will give you the best r-value per inch/mm.
However, for flexibility a batt insulation is your way to go. I also
feel that staying away from a fibreglass insulation is not a bad move either.
Roxul™ uses fibre strands of rock which provide similar r-value, with no itch, something
you’ll appreciate later on.
Just a few points…….