Housing provision for post-earthquake victims requires consideration of the victims' cultural and social needs. Due to limited time and shortage of funds, quick construction of post-earthquake houses often fails to comply with the minimum needs of the occupants. Too often, such houses are either abandoned or transformed substantially, resulting in an overwhelming waste of resources. This paper aimed to investigate the transformation process of post-earthquake houses in Iran, in particular, people's motivational factors for these transformations. The methods used included systematic observations and map analysis of alterations to post-earthquake houses over a 30-year period (1970-2000), interviews with the households and questionnaire survey with 190 respondents. The results recommended that the design for these houses should address potential for transformability into pre-earthquake patterns and lifestyles, adaptability to new parts/construction and capability to reflect different requirements for indoor and outdoor spatial circulations. Analysis of house transformation in the 30-year period revealed that the majority of respondents were found to favour vernacular architecture design, which includes a courtyard in transforming their houses (51.1%) followed by the desire to follow the current trend (32%). The majority of houses had undergone major transformation, having added more than 98% of the original built-up area to the houses. This research found that the mixed 'Temporary- Permanent' housing reconstruction model was highly successful since it involved participation of end users from the very early stages of design and development in order to predict and accommodate later housing alteration issues.