Assuming your lot is strata title, there would be a stratum statement on the plan. The area above the tiled surface of the tiled terrrace is the responsibility of the lot owner. Any waterproofing on the tiled terrace is common property, the repair and maintenance being the responsibility of the owners corporation. All roofing is common property, the repair and maintenance of which is the responsibility of the owners corporation.
Further information is available from the Strata Plan Section of the Land and Property Management Authority, GPO Box 15 Sydney NSW 2001.