Dar es Salaam (Tanzania) is one of the fastest growing cities in sub-Saharan Africa. As in other sub-Saharan cities, government housing programmes have reached only a tiny percentage of urban residents. The vast majority either build for themselves or live as tenants in swahili houses provided by others. This paper examines the process of house building in Dar es Salaam through a survey of 90 house-owners in nine low-income settlements in the city. It is shown that in the past decade the price of manufactured building materials has risen steeply following the implementation of liberalisation policies. Despite this, house owners still strive to build modern houses in concrete blocks, which offer higher standards of comfort and security as well as bringing in higher income from rents. Those who cannot afford to do so, are obliged either to rent one or more rooms in a house constructed by others or to build a modest house using traditional materials. Although these materials are available in the market, some housebuilders still collect their own. There is evidence of increasing distance from the source, the substitution of inferior species and declining quality, all of which indicate that resources are coming under pressure.