3. ROOFING WORK Flat Roof Water Proofing Works Supply & fix one layer of 3mm thick & second layer of 5mm thick fully burnt water proofing membrane laid perpendicular to first layer in APP modified bituminous glassfibre with polyster from "SARNAFIL" or "SIKA" or similar "approved" waterproofing material to concrete flat roof laid with all necessary overlap at joints as per suppliers instructions. Ditto but fix membrane up and over parapet walls including overlapp with slab waterproofing membrane, under flashings, roof access hatches, around vent pipes, curbs, angles and end profiles and the likes on roof as necessary.