Providing and laying four courses of water proofing treatment with bitumen felt over roofs consisting of first and third courses of blown type bitumen grade 85/25 applied hot @1.20kg per sqm of area for each course, second course on roofing felt type 3 grade-I (Hessian base self finished bitumen felt) and fourth and final course of stone grit 6mm and down size or pea-sized grit spread at 0.006 cu.m per sq.m including preparation of surface complete.