Due to rapid urbanisation, land prices have escalated significantly and multi-storey buildings with flat roof slabs have gained significant interest. Flat roof slabs have many advantages such as land recovery, cyclonic resistance, the possibility of future vertical extension and utilising as an extra working space. Since the insulated roof slabs can reduce the energy consumption, an effective insulation system was decided to develop. Ultimately, a structurally sound, thermally effective and durable system was developed with locally available materials with the capability of withstanding 4MT point load. Actual scale model testing showed that the new system performs well in thermal aspects as under actual conditions. Further, a peak cooling reduction of 20% was achieved through numerical modelling. The new material invention process proved that a confined air gap with bamboo strips have a similar thermal performance as polystyrene. Also, vegetation layers on these systems can enhance the thermal conditions. Further, Life cycle cost analysis indicated an additional 5% of the initial cost is paid back within seven years.