Extra for providing heavy sheet float glass panes instead of ordinary float glass in glazed doors, windows and clerestory window shutters. (Area of opening for glass panes excluding portion inside rebate shall be measured)
9.11.15.0 mm thick (weight not less than 12.50 kg per sqm) instead of 4 mm thick (weight not less than 10 kg per sqm).
Matches DSR 2023Vol 1, pages 487 to 488