When a Development is complete, the Developer in question is obliged to form a Management Company.
As each unit in the development is sold the purchaser becomes a Member of this Management Company. This enables a transfer of ownership and therefore control of the Common Areas within the development. When all the units are sold the developer usually conveys the common areas via his/her solicitor to the Management Company and the owners take control of the Company.
In an existing development, it is imperative that a healthy Sinking Fund is in place for every Residential Development. This is now a requirement by law in conjunction with the MUD Act 2011.
This is now a prerequisite if you wish to sell your Apartment.