Many African countries have experienced a large increase of urban population during the last 50 years. The proportion of people living in informal settlements is in some cities as high as 60% (Muraguri 2011), which clearly demonstrates how the demand for low cost housing has been urgent for a very long time. The main aim of this thesis is to analyse the slum upgrading situation in Kenya, focusing on house design, implementation methods and alternative building materials, with the purpose to present advantageous approaches that can be enforced in future development. The project was carried out as a field study in Nairobi during September-November 2013. It evaluates four current or recently completed slum upgrading housing projects in this region. It has a technical perspective, while other also important aspects, such as political and economic influences, are not included in the scope. The results show that many appropriate house designs, implementation methods and building materials are available, but not always all applicable or suitable in any given housing project. Highrise concepts have proven to be devastating for the social and commercial environment of its tenants, while smaller multi-storey houses, with one household living in each, represent an alternative in densely populated areas. Longterm, incremental expansion can also be an advantageous concept.