This research proposes a quantitative evaluation of residential design inequality and housing affordability within public sector employee housing schemes in Lagos State, Nigeria. Despite substantial government investment in staff housing programmes under the Lagos State Staff Housing Board, persistent affordability gaps and design disparities suggest that intended beneficiaries—particularly low- and middle-income civil servants—remain underserved. The study adopts a cross-sectional survey design grounded in the positivist paradigm, targeting residents across selected public sector housing estates in Lagos State. Using structured questionnaires, data will be collected from household heads in six local government areas with high concentrations of public sector employee housing. Stratified random sampling will yield approximately 500 valid responses, representing a population of 1,148 dwelling units across 48 estates. Quantitative data will be analysed using descriptive statistics, Pearson correlation, multiple regression, and the Price-to-Income Ratio to assess affordability thresholds and design satisfaction indices. The research contributes a novel Design-Affordability Equity Framework that integrates residential design evaluation with affordability metrics, offering an empirically grounded model for assessing whether public housing schemes achieve equitable outcomes. Findings will inform policy recommendations for the Lagos State Staff Housing Board, the Ministry of Housing, and federal housing agencies, promoting evidence-based interventions that align housing design and pricing with the actual income realities of public sector workers. The study addresses a critical gap in the literature on residential design inequality in Nigeria's public housing sector, where design quality and affordability are typically examined in isolation rather than as interconnected dimensions of housing equity (Akinola et al., 2024; Oyedele, 2026).