Changing land-use metrics in mass housing: Türkiye case study

Over the past three decades, Turkish cities have experienced significant increases in terms of building densities. This densification is evident not only through taller buildings and increased floor numbers, but also in the balance between built areas and open spaces and the reduction of amenity areas. This study examines the relationship between building density and land use in mass housing projects through objective, measurable and comparable parameters. The research focuses on eight publicly developed mass housing projects in Kocaeli-İzmit, Türkiye. A descriptive mixed-methods case study approach is used together with quantitative analysis of direct measurement and longitudinal comparison of land-use metrics, e.g. floor area ratio (FAR), building coverage ratio (BCR) and building proximity index (BPI). Amenity provision is assessed through normalised per dwelling-unit calculations. These objective measurements are supplemented by qualitative thematic analysis derived from semi-structured interviews (n = 15) with sector professionals, providing causal insights into the observed design shifts. The study demonstrates increasingly higher building densities in housing projects and less open space. This highlights the need to review land and urbanisation policies that cause density intensification. POLICY RELEVANCE This study identifies a structural shift in Türkiye's public mass housing, moving from social-benefit-oriented models toward systematic density maximisation. Empirical analysis reveals a consistent trend of increased densification, while green spaces and amenity provisions decline. A critical finding for policymakers is the 'excluded area loophole', where regulatory frameworks allow specific building components to bypass official FAR calculations, leading to higher realised density than initially planned. To ensure long-term urban liveability, key actions for practitioners and authorities include: (1) reforming zoning legislations to close loopholes that allow the exploitation of 'excluded areas' so that the expansion of building mass beyond environmental capacities becomes possible; (2) integrating spatial quality metrics, such as the BPI, into planning standards to serve natural light and ventilation; and (3) isolating amenity provision from market-driven land-cost pressures through targeted government interventions and subsidies.