One of the factors that gives quality to residential spaces in different periods, is decoration which is appearing in various kinds. In diverse periods, architecture provides a decent foundations for several other arts. Such as Calligraphy, Plaster molding, mirror decoration, Paintings and etc. These kinds of art have an important role by giving quality to the architectural spaces. According to this fact, lots of relics from Iranian famous artists are left as a memorial in historical places. Nowadays, different approaches of architecture and decoration disunites these arts, consequently, the role of each one in giving quality to space, is separated from each other and become less important. In this regard, a relevant question is "What was the role of decoration in giving quality to residential space?" and another question related to it, is; "Is there any relationship between decoration and architecture?" the other question is also, "Was there any system or organization for the presence of decoration in the residential space?"
To answer these kind of questions this paper investigates the state of decoration in past architecture. The authors had been using descriptive, analyzing and measurement methods in order to present the relation of decoration and architecture quality. On the other hand, evaluating the role of decoration especially wall-painting in the quality of residential space is the main purpose of this article. To achieve this goal, Yazd Shafipour house is chosen as a worthwhile case study. The authors have been used questionnaires, conducted interviews and documented their observations in order to obtain a precise investigation. Investigate the role of these decoration especially paintings in the quality of spaces and describes how these various “Art” is an uncountable noun. Replace “kinds of art” to make it countable. Appear in different spaces of Yazd Shafipour house. After that, by considering the decoration of this house, this paper classifies and describes all kinds of decoration that is used in Yazd Shafipour house. At the next step to evaluate the role of Yazd Shafipour house's decoration in the terms of its spaces, some questionnaires has been prepared and given to architecture students. Finally an analytical strategy has been has been employed and the result of these studies presents in the form of charts and tables. These results indicate that decorations have had a significant impact on the quality of the spaces in this house.
This article presents the order of facing with decoration for space designing. It also determines the importance of decoration in residential spaces. The final result indicates that decoration has a significant role in residential spaces. The most important role of decoration, especially wall-painting, is improving the quality of architectural space. It also has important components that play a fundamental role in the design process of architecture design for legibility and identity to the spaces, and designers must pay attention to the type of decorating and its amount proportional to space. The results of the studies showed that decoration have at least three different roles in the quality of a residential spaces:
1.     Decoration promote the qualitative characteristics of space
With the advent of decorations, many qualitative features of space, such as artistic, imagination, complexity and diversity, are promoted.
2.     Decoration moderate and then promote the qualitative characteristics of space
Decoration in the first stage acts as a moderator of qualitative characteristics of space, and in the second stage it improves the quality of space. The traits included in this category are: dignity, beauty and perfection.
3.     Decoration moderate the qualitative characteristics of space
Decoration actually moderate some qualitative traits of space, and with increasing decorations the definite traits do not change. Traits that are balanced by decorations are: order, unity, calmness and greatness.
The results of this article will be used by designers and artists to give quality to the spaces they create.