Assessment of Roof Garden Feasibility in Commercial Buildings in Abuja Phase 2 Districts

Roof gardens and green roofs represent an architectural strategy for urban heat mitigation, stormwater retention, and amenity space creation that is gaining traction globally but remains minimally explored in Nigerian commercial building practice. This study assesses the feasibility of roof garden installation on commercial buildings in the Abuja Phase 2 district developments, examining structural capacity, rooftop access configurations, waterproofing substrate condition, and economic viability of retrofit installations. Physical surveys of twenty commercial buildings in the Central Area, Wuse, and Garki districts were conducted, recording roof structural system type, slab span and load-bearing capacity estimation, access arrangements, existing waterproofing conditions, drainage connections, and mechanical services rooftop installations that may compete for usable roof area. Feasibility was classified on a three-tier scale based on structural and access adequacy. Stakeholder interviews with ten building owners, five facility managers, and five horticulture contractors provided economic and maintenance perspectives. Cost analysis compared estimated retrofit costs against potential rental income from accessible roof terrace space. Results indicate that eleven of twenty assessed buildings demonstrate adequate structural capacity for extensive green roof systems without structural reinforcement, and six show capacity for intensive roof garden installation. Waterproofing replacement is required as a prerequisite in fifteen buildings. The economic analysis suggests a payback period of seven to twelve years for revenue-generating roof terrace conversions in the Abuja commercial market. The study recommends pilot programme support from the FCT Environmental Planning Authority and inclusion of green roof incentives in the revised FCT building regulations. Keywords: roof garden, green roof, feasibility assessment, commercial buildings, Abuja.