Abstract: Over the past two decades, compact city ideas have become entrenched as the planning orthodoxy to deliver the future city. High profile brownfield regeneration projects have been the public face of compact city policies, however there is increasing expectation that future growth will be delivered in existing built up residential areas. Almost all focus has been on the renewal potential of existing single titled land parcels. Virtually no consideration has been given to how existing multi-unit stock might be periodically renewed now or in the future. This paper develops a model to test the feasibility of the renewal of existing multi-unit housing across the Sydney Metropolitan Region and aims to demonstrate the practical outcome that would be required for redevelopment to occur under ‘business as usual’ scenarios. The model demonstrates that left to the ‘market’, strata renewal is only likely to occur in locations where land values (based on replacement units) are sufficiently high enough to drive redevelopment or when densities are significantly increased above existing permitted levels. The paper will first argue that under market conditions, if these generalised observations are extended over a long time period, the outcome of market driven strata renewal will be a highly fragmented, piecemeal intensification of existing residential areas. Second, the possibility of systematically increasing density every 30 or 50 years as the mechanism through which urban environments are updated is both undesirable, and logically impractical. This model also raises the issue of how low value strata blocks reaching the end of their physical life will be replaced when there is insufficient value in the land to support their replacement.