The sequence of physical improvement in self-built houses is replicated by a model of technology diffusion that addresses the inter-relation between spatial and social processes, and captures the dynamics of house upgrading in blocks located within informal development areas in Lima, Peru. Simulations generate accurate spatio-temporal descriptions that characterizes the actual dynamics at the block scale. Moreover, the separation of the spatial and social structures allows to relate upgraded, susceptible and delayed components of the social network with the number of consolidated houses in order to explore the adoption of upgrade conditions. These empirically based experiments have policy implications related to the timing of tailored intervention at micro-scale for current efforts related to providing property deeds and financial support for individuals located in informally developed areas in Lima.