Abstract
The Iranian house is full of structural units. The cohesion of the units creates more complex patterns, which, as a result of their location in different parts of the building, also form its physical structure and functional and cultural characteristics. Since the combination of these patterns in the home is always a reflection of the customs and lifestyle of residents and local conditions, knowing each of the patterns allows them to be used on a larger scale in the design of new homes. The content of structural patterns and the extent of their impact on Iranian-Islamic residential architecture is the basis of research inquiry. The research intends to take a physical approach to express the structure of the architectural language of the house in the sample buildings of the Qajar period; and in this way provide the basis for restoring the architectural values of the past. The research method is descriptive-historical and the method of finding research is a combination. The basis of observational studies has also been done through the presence of buildings that have a relatively complete architectural composition, and citation of existing maps, images and texts. The abstracted contents with the help of AutoCAD software introduce the basic units in geometric shapes and check their applicability in 50 houses of historical-cultural value. One of the important results of this search is the generalizability of the logical order of the initial units identified in various combinations and the production of more complex spatial units than the initial units of 5040 patterns. The results show that the patterns participate in various proportions from 0.06% to 27.16% and 42 in selected houses. Among these, pattern number 8 has the most (453) presence; while Patterns 12, 33 and 42 have the least (1) applications.
Keywords: Iranian-Islamic Architecture, Architectural Model, Architectural Physical Order, Language of Architecture, Qajar House.

Introduction
Due to the common economic and social prosperity, the residential houses of the Qajar period define a rich language in architecture that can be extended to Iranian-Islamic houses in the contemporary and future periods. Field studies show that there are a variety of patterns in residential homes that are physically part of a sequential structure and order. From the coherence of these initial units, more complex patterns emerge, which, according to their location in different parts of the building, express the physical structure and functional and cultural characteristics of the building. Since the combination of these patterns in the home is always a reflection of the customs and lifestyle of residents and local conditions, knowing each of the patterns allows them to be used in the design of new homes on a larger scale.
Housing construction in the contemporary era of Iranian architecture and urban planning, especially in recent decades, has found significant differences with the previous era. Field studies and observations indicate a significant reduction in physical-cultural values arising from new housing methods. For example, the gradual obsolescence of the middle fabric of cities is an issue that easily causes their instability. 
This study tries to identify the past methods in housing architecture and highlight the points of emphasis in its structures and concepts, and then shaping those features into a new format, introduce the most important effective spatial patterns in order to improve the physical and quantitative structure of modern house.
According to historical background of home architecture in Iran, and the need to review the structure of modern home architecture, research seeks to find answers to these questions: 1- What are the basic spatial units in the architecture of the Iranian-Islamic house? 2. What patterns does the spatial order of the units create? 3- What is the frequency of these patterns in the existing samples?

Survey of Basic Spatial Units
The research has summarized the data using a descriptive-historical method. A review of studies conducted by researchers and experts in Iranian and non-Iranian architecture and urban planning confirms the similar and sometimes different points of view of the linguistic structure of Iranian-Islamic architecture. Each of the statements has somehow emphasized the characteristics of Iranian-Islamic architecture; and they are summarized at the crossroads of the world of meaning and the world of matter and are located in six directions (Falamaki, 2012, 194).
In the Iranian- Islamic culture, it is believed that matter or the material world is opposite to light or the spiritual world (Holy Quran, Esra: 70). In Iranian-Islamic architecture, the spatial arrangement of the body shows that, in its spatial organization, attention is directed from light to matter. In fact, “it is a journey from pure light to the depths of matter” (Holy Quran). Although architecture is shaped by the combination of matter and space, form is created by the domination of space. Therefore, the form depends on the arrangement of the initial units that make up the architecture of the building. These units include a closet, room, living room, hall, porch, Platform, courtyard and basement.
Examination of the frequency of practical application of patterns in sample houses shows that out of a total of 42 patterns used, pattern No.8 has the highest presence among the 42 units; Patterns No. 12, 33, and 42 have the least presence in the composition of houses. Among the most complex patterns, pattern No. 1 with 15 times the company had the least and pattern No. 18 with 40 times had the most use. The results also show that the patterns contribute in various proportions from 0.06% for patterns No. 12, 33 and 42 to 27.16% for pattern No. 8 in the sample houses.

Conclusion
The seven structural foundations of house architecture in Iranian-Islamic, including: basement, room, living room, hall, porch, platform and courtyard are clearly recognizable. Each of these seven primary units is distinct due to its purity and structural simplicity. The reason for the differentiation of the primary units is their placement in a successive series from darkness to light. For this reason, these units are turning points in marking the evolution of syntax and syntactic language of Iranian-Islamic housing architecture, and their location in the series of units generates patterns that allow them to produce a significant variety in housing architecture. In order to accept this theoretical view, field observations on houses of historical-cultural value make the existence of diversity correct. Based on factorial 7 mathematical calculations, there are 5040 possibilities for the logical arrangement of the initial space units and the production of a pattern; while according to field observations, only 42 possibilities have been used in sample houses so far. Primary units, in part or in whole, can communicate with other units in four directions. Studies show that the two directions of north-south and east-west are the most important patterns in terms of complexity and the extent of their use in Qajar period houses. Patterns together create a large, controlled space that joins together in hot conditions to create a larger space; while in cold conditions, these spaces separate from each other and create small and independent single spaces.
The coherence of the patterns in both longitudinal and transverse directions shows that the design language of the Iranian house, based on the flexibility of the constituent patterns in practice, has the ability to create newer examples. The flexibility of the patterns is affected by the integrity of the initial units, which is provided by adding and subtracting some initial units in the form of order.