The sustainability aspect of industrialized massive blocks of flats in Bcograd is analyzed through the possibility of the industrialized building model - BM to be upgraded (not demolished), on different levels of its composition. Flexible use and transformation capacity of 13M may be a solution to convert massive housing into a more adaptable building. To provide a maximum of possibilities during the lifespan of the building, the flexibility issue needs to be analyzed on different levels of building composition. Industrialized housing in Beograd had been systematically built according to main building functions: load-bearing, enclosing, servicing, intill partitions and equipment. Integration of prefabricated components, subsystems and systems into building iriodcls and joint technology arc of interest for sustainable transformations of post-war housing. The graph model (GM) toll will be applied for evaluation of dependency conditions and accordingly, possibility for transformations on different levels of industrialized model composition. Physical characteristics of BM arc of interest: construction system, systems and components assemblies and joint technology.