The Limits of Upzoning: Historic Land Use, Amenity, and Lot-Scale Drivers of Densification

Problem, research strategy, and findings Upzoning has been characterized as a critical solution to increasing housing supply. However, its effectiveness is challenged by persistent gaps between zoned supply, planning approvals, and actual construction. The influence of lot size, historic land use, and proximity to infrastructure on feasibility of redevelopment on upzoned lots is rarely quantified. As a result, planning systems may overestimate the capacity of upzoned land to deliver new housing, overlooking the complex interplay of regulatory history, physical site characteristics, and market dynamics that ultimately shape development outcomes. In response, I examined factors influencing apartment and townhouse construction on individual lots in Brisbane (Australia). Key predictors include zoning categories (including historical zoning changes), historic land use, proximity to amenities, and lot size. The analysis reveals that upzoning alone was an insufficient driver of change, and that lots formerly used for industrial purposes in 1951 (often riverfront, inner-city areas) and larger lot sizes were significantly more likely to contain higher-density development in 2021. The effect of lot size plateaus beyond 1,200 sq. m (∼13,000 sq. ft), suggesting that additional constraints limit development feasibility, despite ample land. The influence of zoning likely reflects regulatory requirements in traditionally zoned jurisdictions, where higher-density zones are explicitly needed to permit such development.Takeaway for practice Zoning functions as an essential enabler of densification in Brisbane but does not alone catalyze new construction. Unless market conditions are strong, the translation of increased zoned capacity into actual housing supply takes time. Upzoned sites in low-demand locations may potentially never materialize into increased housing supply. Conversely, restrictive low-density zones remain effective at constraining new development, underscoring zoning’s role as a necessary (but alone, not sufficient) condition for densification. Importantly, findings show restrictive zoning can shape built form for generations, despite subsequent upzoning.