20mm Cavity Drain Membrane for Basement Floors. Newton 520 is a BBA approved cavity drain membrane suitable for use above basement floor areas. The 20mm studded membrane allows for a massive flow rate to pass underneath the membrane and is specified where floor areas are of questionable quality or where it is anticipated that there may be a risk of severe water penetration. Newton 520 is available in roll sizes 2m x 20m - 40m (M4) or 2m x 10m - 20m (M13)Typical Applications - Applied to existing and new slabs which are of questionable quality
