The traditional architecture of the Indonesian archipelago is probably one of the most diverse in Southeast Asia, as a remarkable amount of cultures and hence building traditions evolved almost isolated from each other, over centuries. Those typologies are extremely well adapted to culture, climate, and local resources and therefore presenting a variety of possible solutions for socially and ecologically sustainable construction methods in the complex hot and humid tropical climate zone. Yet those local solutions are increasingly disappearing in favour to westernized building typologies, including the replacement of organic construction materials with synthetic substitutes. The research focuses on the motives for those transformations and the question for a possible sustainable and healthy alternative, by integrating traditional principles into contemporary building tasks. After a history of colonization, suppression, following independence and globalization, those events had a huge impact on not only society and economy, but as well on the building sector. As industrial building materials became cheap, easily available and well promoted, they are currently more and more replacing traditional construction materials and therefore provoke a subtle disappearance of the elaborated methods of Indonesian vernacular architecture. Especially in the rather rural and suburban areas the yearning for modernisation and catching up with the global world is resulting in a rapid transformation towards constructions, which are mostly unsuitable for the tropical climate. Due to the inadequate use of 'western' materials and building typologies, which originate from an entirely different background, this change results in unhealthy, uncomfortable and hardly sustainable residential architecture. The efficiency of the local constructions is directly linked to the materiality and synergy of its components, therefore one has to be careful to avoid an unsuitable replacement with substitute materials, such as corrugated iron for thatched roofs, or reinforced concrete for timber walls. Following on-site documentation on the islands of Sumatra, Sulawesi and Bali, the aim of this research is to identify the performance of vernacular design principles and craftsmanship in those economically, environmentally and culturally differing regions. Further investigations on the current material and typological changes in the rather traditional rural areas, as well as on the motives for such transformations offer a deeper understanding of the driving forces for those culturally complex processes. Regarding the long tradition of building local, there are currently tendencies towards integrating, supporting and improving traditional craftsmanship and materials and combining them with local knowledge and modern technology. To mention a few, some popular adopted principles are microclimatic improvement by the use of natural cross ventilation, e.g. through thatched roofs and permeable walls, the elevation of buildings, the use of large roof overhangs for shading and experiments with local organic building materials. The individual motives for changes in construction methods, especially regarding unregulated settlement architecture, are the result of a complicated chain of historical events, westernization, globalization and as well recent changes in culture and ecology. Nevertheless one of the most crucial factors for such choices is the perception of the family home as a prestigious object, a symbol of wealth, status and cultural traditions. In the housing sector traditional building concepts and materials are diminishing in their prestigious value, as they interfere with the image of a modern way of living. At the same time traditional elements and local materials are being rediscovered and integrated into contemporary architecture, still mostly romanticized tourism and gastronomy projects, but also often in an innovative combination with modern technologies and thoughtful use of both natural and synthetic building materials. Following international attention and further spreading of such concepts, they could act as role models for an authentic and sustainable Indonesian architecture, which provokes a modernisation of the term 'vernacular', embraces the traditions and develops them into a contemporary language. Interestingly enough, it appears that especially craftsmanship is an indicator on how closely intertwined architectural forms are with traditions, symbolism and identity. No matter how modern a building gets, no matter how materials and construction methods change, there will hardly be an Indonesian house without elaborate details, ornamented facades, or at least attached symbols and crafted interiors. There are various ways to translate traditional and local design principles into present day architecture, yet this is often only reflected through a simple application of vernacular items to concrete walls or copying traditional buildings for the creation of romanticized tropical utopias. Without an understanding of the great technical value of the diverse vernacular art of building in Indonesia and the strong connection of indigenous architecture with culture and environment, there cannot be an authentic contemporary building language. A sensitive contemporary interpretation of vernacular principles could open the discussion for the future of Indonesian architecture, as this trend is producing prototypes for a sustainable Indonesian architecture, which is at the same time respecting traditions and promoting craftsmanship, but still embracing modernisation and development.