XL Underlay

If your subfloor suffers from some minor dips (up to 3mm) XL Underlay can help solve the problem. It's made from lightweight extruded polystyrene and comes in packs of 10 tiles that are 500mm wide by 1200mm long. It offers exceptional sound and thermal insulation, and when taped together forms an effective moisture barrier. Tog rating: 1.7.