PurposeThe courtyard form of the traditional African house responds to people's culture and traditions. Nevertheless, in the era of globalization, the private open space (POS) is fast disappearing in African homes due to neglect and lack of awareness of its value. This study, thus, aims to explore how culture relates to open space design in traditional houses of three major ethnic groups (Hausa-Fulani, Yoruba and Igbo) in Nigeria. This is with a view to encouraging planners and designers to create open spaces in housing developments according to people's cultural values and needs.Design/methodology/approachThis study is based on qualitative and quantitative research approaches involving a literature review, focus group discussions and a questionnaire survey. The quantitative survey was designed based on the literature review of the concept of culture and the use of space in traditional courtyard houses. Focus group discussions were conducted to identify the specific cultural components that dictated the use of the courtyard as a POS in the Nigerian context. Subsequently, a questionnaire survey was carried out to determine the importance of each cultural component in the outdoor sociospatial design. Through systematic sampling, one of every five traditional houses in the study area was selected to determine where respondents were surveyed.FindingsThe results reveal that the cultural components that influenced the design and use of the open space were gender and privacy, family and social relations, religious practice and belief, and status and lifestyle. However, the importance attached to each of the cultural components varied from one culture to another in Nigeria. The findings also showed that the open space is used for a variety of purposes, such as ancestral worship, family gatherings and reunions, small-scale ceremonies, and leisure activities.Research limitations/implicationsThis study offers professional planners and designers helpful insights to protect culture in housing development and improve daily living in residential environments.Originality/valueBased on Amos Rapoport's theoretical framework, this study dismantles the concept of “culture” into different components and examines how they affect outdoor sociospatial design in a developing country. The study also provides researchers with ideas and inspiration to study the culture of POSs in traditional housing.