The impacts of regulations and legislation on residential built forms in Tehran

This paper addresses the challenges posed by the framing of planning law, as it affects the built forms of cities. These are challenges faced by many cities worldwide, especially those undergoing rapid change. The paper explores the role of planning controls and building regulations in shaping the built form of one of the world’s fastest growing cities, Tehran. Comparisons are drawn with the historic and contemporary effects of regulations in Paris, New York and Hong Kong. There are generic implications for planning legislation in other cities. The approach taken to the research is a combination of historical investigation with some simple geometrical analysis of housing layout. The built form and urban layout of Tehran’s residential streets in particular seem to be the result of a complex process of limits imposed by planning codes and generic functions together with cultural changes and desires for modernisation. However, the influences and effects of urban parameters such as block size and proportion, as well as built form parameters such as building shape and depth are mediated by building regulations. Starting with a brief introduction to the housing sector in Iran, some primary and extremely influential housing regulations are discussed in the paper and an investigation is made to find out where they came from and the reasons behind their enforcement. The paper uncovers the role planning codes have played not only in limiting and regulating but also, as an indirect effect, encouraging and introducing new types of house. It also briefly presents the effects of regulations in other cities like New York and Paris to demonstrate that simple physical codes can have large morphological and aesthetic effects on the cityscape. It is argued that these regulations are enforced with the purpose of controlling the quality of the built environment and preventing over-crowding; however, their secondary and unintended effects on the quality of cityscape, street facade and the interior of buildings (in terms of day-lighting and ventilation) have not been considered at the appropriate scale. The paper concludes with some remarks about the importance of regulations, not only as tools to control the quality of the built environment and the overall density, but also as shaping forces in determining the built forms of cities, in their parts (buildings) and the cityscape as a whole