I am building on top of my existing external cavity wall that has had a shoddy cavity insulation job done. One corner is missing a fair bit of insulation. So I thought I would just top that up first before building the new wall above with slabs in it. The issue I have come across is I am struggling to find anyone listings such a product. I may just be using the wrong name or something but if anyone could point me in the right direction it would be most appreciated. Thanks