## 2 Literature Review
### Factors Affecting Quality
\begin{table}
\begin{tabular}{c c} \hline \hline
**Authors** & **Statements** \\ \hline [PERSON] et al. [15] & The most common defects included uneven painting, nail marks, poor quality finishing of rooms and floors, improperly fitted door and window handles, cracks in buildings, and the incorrect installation of toilets. \\ [PERSON] et al. [16] & The most common construction defects in new homes are cosmetic. \\ [PERSON] and [PERSON] [1] & Most defects in these buildings were often hidden and appeared during the building’s use. \\  & Therefore, repairing these defects becomes difficult and expensive because access to the source of the defective components in the completed building may be difficult. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Cont. poor quality of project management, delays in decision-making, a lack of control in the investment process, cost and time pressure, and also poor communication between the designer and the contractors. The important role of training and education in the field of management in the context of identifying the correct technical solutions was also indicated. In addition, the phenomenon of corruption can also be seen to be of great importance for the quality of buildings. This is particularly visible in developing countries [21]. The design phase and the proper preparation of design documentation is of key importance for the quality of buildings under construction. [PERSON] et al. [28] identify the main factors that affect the occurrence of defects at the design stage of residential buildings in the Gaza Strip. For the purposes of the analysis, a survey was carried out which identified three main design errors: ignored or incorrectly performed soil tests, a lack of qualified supervision of drawings, and inconsistency between architectural and construction drawings. In addition, the authors of studies [20,22,24] point to the quality of the design, namely poorly made project documentation [20], the ambiguity of design details, and the introduction of changes to the structure of the facility [22,24]. During the construction and operation phase, attention was paid to the type and location of the building, climatic conditions, occupational safety challenges during project implementation, the lack of inspection and inadequate supervision on the construction site, the lack of required maintenance, as well as changes with regards to using the facility [17,20,22]. Based on surveys conducted among employees of design offices, consultants, contractors and building owners who are responsible for the design, execution, and maintenance of residential buildings, it was shown that the assessment of the impact of factors on quality depends on the evaluating group [23]. Contractors considered architectural design flaws to be the most significant, consultants considered defects resulting from the technical specification as the number one factor, and clients considered defects in the architectural design as the most important. The authors of many studies emphasize the importance of controlling the construction process to obtain a high-quality product [4,21,22,24,25]. [PERSON] et al. [4] analyzed various quality control factors in housing projects in Spain. Based on their research, they proposed changes regarding control, which involved paying attention not only to the management process but also to the quality and control of the supply of materials. [PERSON] et al. proved that the size of the development company and the location of the building also have a significant impact on construction defects [29]. The occurrence of defects in residential buildings is associated with the need to remove them, which in turn generates significant costs. Based on research conducted by [PERSON] et al. [30] in Australia between 1982-1997, it was found that the cost of repairing defects is about 4% of the contract value. In turn, [PERSON] [26] found that the cost of repairing defects corresponds to 4.4% of the construction costs of buildings, and the time to repair them is 7% of the total working time.