Was at the self build show in city west at the weekend. One of the companies doing insulation was there and I asked about attic insulation. When I asked about their board insulation for attic storage the lad, very honestly, told me that their product was a waste of money. I should get a sheet of PS insulation board and fix to joists and then put normal board over this and secured. Probably a stupid question but is this as simple a solution to save a bit of money instead of the much more expensive insulation boards sold specifically for this purpose? Any draw backs?