The dome, one of the most stable forms of roof coatings, has passed many of its evolution stages in the dome-chambers of Iranian mosques. From the Seljuk era, when the first dome-chambers were seen, to today, the extent of the openness of the dome-chamber space to the adjacent space – shabestans and the porches - has changed a lot. This research seeks to answer the questions of why and how openness have happened and what factors have influenced their intensity. Since there may be different answers to these questions at different periods, the physical properties of the domes were studied in terms of measurable variables, both in the general context and in each period. For this purpose, 51 dome-chamber mosques were selected from Seljuk to Qajar periods, with variation in physical characteristics. The research method is a combination of content analysis method, comparative study and logical reasoning based on the descriptive and correlational statistics. As a result, it has been shown that structural constraints related to the extent and magnitude of the dome-chamber, are considered the main reasons for deciding how much and how to open the dome-chamber’s walls in different periods and that as the ratio of the span to the wall thickness increases, the openness of the walls decreases to the same extent. Also, the architecture of seljuk and safavid mosques are more similar than the other periods, possibly due to the common religious characteristics that affected them both.

Keywords