The courtyard has been one of the main spaces in houses, particularly in traditional architecture of Iran, that has played a significant role in the spatial organization of houses. The main question of this research is: What is the relationship between the spatial organization of historical houses with single-courtyard and double-courtyard, and the number of courtyards? The aim of this research is to discover the relationship between the number of courtyards (single-courtyard and double-courtyard) and the spatial organization of historical houses. The required information for this research has been gathered through library resources, documents from the Cultural Heritage Organization, and field observations. The study employs a descriptive-analytical method with a qualitative approach to analyze the case studies. The statistical population consists of (20) single-courtyard and double-courtyard historical houses from the Qajar period in Tabriz. This research was conducted in three stages: In the first stage, the influential factors in the spatial organization of historical houses were introduced. In the second stage, the houses plans were analyzed based on the factors derived from the theoretical framework of the research. In the third stage, the data obtained from the analysis of the samples were compiled and concluded. The study specifically examines the main and selected spaces of the houses, including the entrance, courtyard, Tanabi (main hall), rooms, Iwan (a type of porch), and stairs. Various factors influence the spatial organization of historical houses, and this research focuses on those related to the research topic. One of these factors is the geometry of spatial layout; the study of historical houses architecture often shows that the courtyard is usually a central space, with other spaces and functions arranged around it. Therefore, central and radial layout patterns are more prevalent in studies focused on courtyards. Besides the central and radial layout patterns, the geometric pattern of the spaces around the courtyards, which reflecting the geometric form of the built fronts around the courtyard, is also influential and worth examining in the geometry of spatial layout. Another influential factor in the spatial organization of historical houses is axes. Based on studies, it can be stated that movement axes (internal and external), visual axis, and symmetry axis are the main influential axes in the spatial organization of historical houses. Another factor is hierarchy; in historical houses, hierarchy is more about spatial hierarchy and access hierarchy. According to studies, it can be stated that the elongation of courtyards, the depth of spaces relative to the entrance, and permeability are influential in the spatial and access hierarchy.
In summary, it can be stated that in single-courtyard and double-courtyard houses, various factors such as the geometry of spatial layout (based on central and radial layout patterns, and the geometric pattern of the spaces around the courtyards), axes (based on internal and external movement axes, visual axis, and symmetry axis), and spatial and access hierarchy (based on elongation of courtyards, depth of spaces relative to the entrance, and permeability) collectively indicate a specific type of spatial organization, related to each of the two mentioned types. The research findings show that although these factors are similar in some cases, they also create differences in the spatial organization of single-courtyard and double-courtyard plans. For instance, the study of the geometry of spatial layout shows differences in the arrangement of spaces relative to the courtyard, differences in massing and the number of built fronts around the courtyard, the degree of introversion relative to the type of courtyard, and etc. The study of axes indicates differences in movement paths and internal spatial relationship, differences in the direction of visual axes, the manner of symmetry observance, and etc. The study of hierarchy shows differences in the division of the house's areas, differences in the placement of spaces at various depths relative to the entrance based on their function, and etc.
