This study was accomplished in the context of a broader research to be developed in an ongoing PhD program in architecture. The purpose of this study is to give a perspective of the research progress and to present a shape grammar simplification that will be improved to assist the rehabilitation design process of the bourgeois house of Oporto.The typology of the bourgeois house of Oporto, built from the late sixteenth century until the early twentieth century, is dominant in the ancient fabric of the city and in need of rehabilitation. From the analysis of a representative sample of a moment of its evolution, it is possible to verify patterns and to define rules.This first approach intends to validate the use of shape grammars as a tool, able to assist the architect in the rehabilitation design process of the bourgeois house of Oporto.