This paper discusses some housing examples of the state of Sao Paulo, Brazil, and their user representation. It is shown that official projects have had little impact on the total housing needs in the region and that 60% of residential production is self-built. A sample of the self_building process was analysed in a specific municipality (Campinas, S.P.) to measure the need for professional help in the sector. The sample showed diversity of construction and comfort quality of houses. The difficulty in organising user groups in the local self-building process and the environment of economic constraint call for specific professional intervention especially regarding design of houses. A design tool, based in a popular CAD system, was devised. This method permits efficient attention to user needs and representation of self-builders with a degree of individualisation in house design.