Building a duplex suits people for a number of reasons and the demand for duplexes continue to grow in Sydney, NSW. The nature of the Duplex has changed. Gone are the days of small tight homes with 2 bedrooms and small living spaces. Duplexes have now emerged into four generously sized bedrooms with walk-in-wardrobes, master bedrooms with ensuites, generous storage spaces, and opened plan kitchens and living rooms.