The rise of China to become world largest iron and steel producer and consumer since the late 1990s can be largely attributed to urbanization, with about 20% of China's steel output used by residential buildings, and about 50% for the construction sector as a whole. Previously, a dynamic material flow analysis (MFA) model was developed to analyze the dynamics of the rural and the urban housing systems in China. This model is expanded here to specifically analyze iron and steel demand and scrap availability from the housing sector. The evolution of China's housing stock and related steel is simulated from 1900 through 2100. For almost all scenarios, the simulation results indicate a strong drop in steel demand for new housing construction over the next decades, due to the expected lengthening of the – presently extremely short – life span of residential buildings. From an environmental as well as a resource conservation point of view, this is a reassuring conclusion. Calculations for the farther future indicate that the demand for steel will not just decrease but will rather oscillate: the longer the life spans of buildings, the stronger the oscillation. The downside of this development would be the overcapacities in steel production. A scenario with slightly lower life spans but a strong emphasis on secondary steel production might reduce the oscillation at moderate environmental costs.