Resumen
This paper analyzes the dynamisms of house plans, family stages, and family backgrounds, and their interrelated dynamism, of lower-middle-class families in suburban residential areas in Sri Lanka. Through a literature review of Sri Lankan historical house plans and family units, parameters to categorize house plans, family stages, and background types were derived. Using measured drawings, interviews, and observations of the case study families, data regarding house plans, construction steps, family stages, family backgrounds, and their transition steps were collected, and a quantitative analysis was conducted. The research included identifying lower-middle-class house plan types and transition types, family stages, parents? employment types, and children?s education types. The results show that the transition of family stages and family backgrounds has a relationship with the transition of house plan types, resulting in social mobility and different generations, in different social classes, living in the same house. This study proposes two new house plan types for two construction steps in two family stages, giving a mixed character of lower-middle-class and other social class house plans, providing flexibility to expand and adjustability to cater to residents in different generations and social classes.