According to the remains of ancient historical houses that have existed in many parts of Iran since the sixth millennium BC, each house typically consisted of two parts - one built and enclosed, and the other open (courtyard). The role of geographical and environmental phenomena is clear in the formation of open space or yard of the houses, however, the architecture of housing in every period changes due to the demands and needs of the residents, and these changes significantly affect the aspects and spatial relations of the house. These transformations have led to the change in the closed and open spaces of the houses.
The current research has been conducted with the historical approach using the analytical-descriptive method. Documentation of the architectural features is based on gathering the library sources and field study. To achieve this purpose, some traditional houses of Ardabil dating back to the Qajar to Pahlavi eras have been considered in terms of physical elements and yard patterns. To do this research, 23 samples of traditional houses of Ardabil in the historical area of this city have been identified and then classified. The results obtained from the classification strengthened the idea of the dominance of rectangular form in the design of the houses. Houses with a yard built in a single front have the most frequency among the research samples. Also, due to the location of the Ardabil province in the mountainous regions, most of the days of the year have cold weather, and most of the daily activities are done inside the rooms. Therefore, due to the obtained frequencies, the ratio of open spaces was less than 40% of the site’s area on average.