Prepare the roof after waterproofing treatment as recommended by the Architects / Consultant to make the roof watertight.
Install a separation layer of 150-200 GSM polypropylene/ polyester based   geo-textile  fabric with an overlap of 75 mm and 100 mm on the longitudinal and transverse directions above the waterproofing system.

Install INSUboard Thermal insulation of adequate thickness for achieving desired R or U value  in staggered pattern above the separation layer.

Lay a final separation layer of  150-200 GSM polypropylene/ polyester based geo-textile  fabric with an overlap.

Cover with 300 microns of HDPE film before final finish with cement screed / tiling.

Alternatively, loosely lay paver blocks/ precast cement tiles with adjustable / non- adjustable supports to form an accessible roof.