Isover Spacesaver loft insulation helps improve energy efficiency and reduces heating costs. Now supplied in longer length rolls they are ideal for new build and renovation projects.Isover Spacesaver is a glass mineral wool which provides thermal insulation at joist level for cold roof applications. These strong, resilient and flexible rolls are now supplied in longer length rolls to help increase the speed of installation and ensure more efficient deliveries and storage.The rolls are manufactured in 100-200mm thicknesses, pre-perforated to 3x386mm and 2x580mm widths to fit between common joist spacing.