Post-colonial Nairobi has experienced a rapid urbanization rate averaging 5 per cent per annum from 1963 to the present. The planning framework inherited from the colonial regime and little changed after Independence has not been able to cope with the increased demand for urban goods and services. This has made it necessary for Nairobi residents to seek and source these through informal processes. The informal processes have in turn generated an informal urban process, but since these processes are not homogenous this paper argues for the case of informal urbanisms. The paper traces the origins of informality and argues that informality is not illegal. The paper then examines the informalization of Buru Buru a middle-income estate built in the 1970s and early 1980s. The under provision of social facilities/amenities in this estate has resulted in the residents making alterations and extensions to their dwellings as a mitigating intervention.