The Impact of incremental vertical housing development on quality of space and residential environmental satisfaction: a case study of Swarna place, Colombo, Sri Lanka

This study critically investigates how incremental vertical expansion in low-income housing affects the quality of space (QoS) and residential environmental satisfaction (RES) over time. Using Swarna Place, a low-income settlement in Colombo, Sri Lanka, as a case study, the research examines the transition from single-story core units to four-story structures. Through a mixed-methods approach, the study employs spatial observation, architectural documentation, and resident surveys based on the QoS framework and the Residential Environmental Satisfaction Scale (RESS).The analysis identifies seven stages of physical transformation and evaluates each using six QoS indicators (lighting and ventilation, thermal quality, acoustic quality, spatial layout, functionality, and accessibility) and three RESS domains (internal neighbourhood reputation (INR), dwelling satisfaction (DS), and social climate (SC)). Findings reveal that, although DS increases due to improved housing quality and aesthetics, the overall RES declines in later stages as a result of reduced social engagement and community cohesion. Originally a multifunctional communal area, the ground floor living space becomes increasingly restricted in later stages due to staircase additions and fixed layouts. As vertical growth progresses, the QoS declines, and although residents make minor adaptations to the built environment, these adjustments offer limited relief. The study concludes that unregulated vertical expansion may compromise spatial and social liveability in incremental housing, leading to reduced environmental satisfaction despite physical improvements. It highlights the importance of balancing flexibility with design regulation and resident guidance to prevent the evolution of vertical slums. The research contributes to the discourse on sustainable housing by offering actionable insights into how urban settlements can preserve community identity, functionality, and spatial quality amidst vertical densification.