Torch On Underlay Under Felt 8m 6m 5m 4m 3m 2m x 1m wide 3kg/m THICK
While the IKO 3kg/m² torch underlay is technically about 2mm thick, roofers often refer to it as "3mm underlay" for a few key reasons They're more concerned with the material's performance and robustness than its exact physical thickness.