Model for Reducing Minimum Plot Size Requirements under Land Subdivision Law: Legal Compatibility and Land Use Efficiency Assessment

Abstract

Rising land prices and limited land availability in Bangkok’s inner urban areas have constrained residential development by increasing development costs and restricting land utilization. At the same time, the minimum plot size requirements under Thailand’s land subdivision regulations may not correspond to the development potential of high-density urban areas where high Floor Area Ratio (FAR) allowances apply. This study examines the feasibility of reducing the minimum plot size for micro-subdivision developments by evaluating its impacts on land utilization, building floor area, and development costs within the framework of land subdivision law, building control law, and comprehensive urban planning regulations.

The research employs comparative development models with different plot sizes and building configurations to analyze the relationships among plot size, FAR, usable floor area, and development costs. The findings indicate that reducing the minimum plot size is feasible under existing legal requirements when accompanied by appropriate building design adjustments, particularly through increasing building height while maintaining a comparable amount of usable floor area to the case study project. Smaller plot sizes also reduce land costs per housing unit and improve land-use efficiency by better aligning development with the FAR provisions and urban planning regulations, especially in high-density urban areas.

The study suggests that minimum plot size requirements should be determined in conjunction with land-use potential under urban planning and building control regulations rather than by plot dimensions alone. The findings provide evidence to support the revision of land subdivision criteria to better reflect contemporary urban development conditions, promote more efficient land utilization, and improve housing accessibility in urban areas.