The objective of the Algerian government was to build two million housing units by 2014 to overcome housing shortage. But little consideration has been given to achieve sustainable design and construction within new buildings, where flexibility and variety are necessary to allow residents to make changes and adaptations to their homes. This article reports on a study of two government-provided housing settlements in Constantine, Algeria. Eighty dwellings from social collective housing were analysed to evaluate their sustainability by examining two indicators: satisfaction with spatial organisation and level of flexibility in design. It was shown that many modifications were made, both small and large, to attempt to accommodate changing needs, size of families, and to satisfy new lifestyle aspirations. However, where alterations were made, the consequences were potentially hazardous to buildings and led to rapid degradation. It was suggested that to achieve buildings with longer useful life, future designs should build in more flexibility and better space standards.