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 at 1.20 Kg. Per sqm of area for each course second course on roofing felt type 3grade-1 (Hession base self finished bitumen felt) and fourth and final course of stone grit 6mm and down size or peasizes grit spread at 0.006cum per Sqm including preparation of surface complete.