The Role of Geography and Culture in Formation of House Roof

Introduction
There are many factors on formation elements of architecture, such as environmental characteristics and climatic phenomena as the most important. Some factors such as natural environment and consequently domestic materials, temperature, rainfall, and sun radiation were the most important factors in the past. They had the most effect on the form of architectural spaces. Thus, in the normal condition in the past, the wooden structures were commonly used in the forest and green environments and the mud-brick structures were used in the hot and arid areas.
The materials and structures as the environmental phenomena affected the architectural spaces and the relations between open and closed spaces. They also determined the shape of roof in buildings. Of course, many other factors such as culture and cultural exchanges between nations, the style of life and economic factors were important.
 
Methodology
This research has been prepared using descriptive-analytical method. In this research, the effects of geography and climate on the shape of roof building have been considered. There are some intervening variables such as some forms and elements that have symbolic meaning and were used in some kinds of buildings, especially in ritual buildings. Some foreign elements and forms in roof buildings are other kinds of intervening variables. Statistical society in this research is Iran, but some examples have been used from other countries.
 
Results and discussion
The results of this research show that the shape of building roof was formed on the basis of geographical factors in the first step, as sloped roofs were used in the northern coastal region in Iran with temperate rainy climate, arced roofs were usually used in the central plateau region with hot and dry climate and flat roofs were also used in the most parts of the southern coastal region, with hot and humid climate. The direct relation between climate and roof shape can be seen more in residential units in the past, but in some ritual and some governmental buildings, specially in big and important ritual building, some other factors such as symbolism and to some fashion could be considered. For example, there were examples of some mosques with domes built in a region with sloped roofs of all other buildings, because some people in some periods thought that a dome can be better for a mosque. For example, Akbarieh Mosque in Lahijan, with rainy climatic condition, have some domes, but because of rain, there are a sloped roof on the domes, and people who go to mosque, can see domes in internal space, but in outside, the sloped roof can be seen.
In some other cases, a supreme fashion for some governmental buildings can be observed from past centuries. For example, in Takht Jamshid (Parseh), there were flat roofs, while in that region buildings are mainly structured by domes because there were not enough tree and wood for covering roofs. It seems that usage of that kind of roofs was for making a difference in shape of governmental buildings from the other public buildings at that time. This subject can be strengthened by the old texts that describe they had carried wooden beam from Lebanon to Iran for ceiling roofs. In another field, we can pay attention to some buildings roof, specially the roofs of houses and usual buildings.
Ruff form in ritual buildings can also be related to patterns of cultural values and religious and social factors. Some architectural forms and elements of semantics have been preserved into domestic level, even though materials and geographical conditions or systems of structures. A particular form or element of semantic architecture had gained an important meaning within a religious and cult system. Vernacular architecture was constituted to express harmony in structure components, from the largest elements such as roofs and the whole parts of a building to smaller elements and details.
 
Conclusion
The shape of roof in residential buildings in the past was formed on the basis of environmental and geographical characteristics and conditions. Some geographical factors such as native materials and climate conditions affected the shape of roofs directly but some others affected them indirectly.
In addition to these factors, application of roof as a resting and sleeping place in some seasons in the night was caused that some arced roof transformed into flat roof.
The influence of some cultural factors on roof shape can be observed in ritual and some governmental buildings.
By these discussions it can be concluded that:
-          Roof is the upper part of a building and in addition to having an architectural role; it has an urbanism aspect that can be seen from distant.
-          Roof is at the top of a building; this can be representative of the position of inhabitants.
-          Roof was an important part of a building because it must be resistant against rain and snow.
-          The form of roof could be very important for ventilation in the past.
-          The form of roof in religious building was very important, because it could represent the importance of a building.
-          The roof of a building in the past was the first structural sign of a structure.