I’m sure I’ve seen an advert for a product (metal/plastic things?) to raise the joists to make it easy to board over thick insulation, but I can’t find it now I need it. Is it expensive? I’m getting a builder to do the work so would it be just as easy/cheap to get him to raise the joists with wood? He suggested screwing down tongue and groove to squash the insulation, but I assume that woud reduce the effectiveness of the insulation? Can anyone help please?