## 2 Literature Review
### Defects Found in Residential Buildings
[13] pointed out the great importance of the inspection of construction processes by future owners. Although inspections take place during construction or at the time of handover, clients usually do not participate in them. This situation creates a gap between the quality perceived by both contractors and customers. The article presents an analysis of 52,552 acceptance defects in 2179 apartments in Spain, identifying their nature, construction element, and the industry in which these defects are found. These results were compared with previous studies that analyzed defects detected at the construction stage and those that remained after the building was handed over to the client. Studies have shown that construction defects are removed during construction thanks to existing quality standards. However, aesthetic and functional defects remain at the time of delivery. The authors conclude that many functional defects result from the lack of end-user involvement in the early stages of the project. Similar studies were conducted by [PERSON] et al. [14]. The article presents research on the most common building defects at the time of handing over the buildings for acceptance, the causes of defects, the consequences for the main contractor, subcontractors, users and customers, and the possibilities of improvements (repairs). The results show that the most common defects recorded at the time of handing over the building are defects related to surface damage. Repairing them is neither difficult nor expensive. Another area where the most common negative deviations occur are defects related to technical installations. Unfortunately, this is often a serious problem because it prevents the entire building from fully functioning. The main cause of defects is incompleteness and poor design, and the main consequences of defects are economic losses and erosion of trust between the various stakeholders in the construction industry. [PERSON] et al. [15], using 216 residential buildings commissioned in 2008-2011 in New Zealand, determined the level of detection of defects by independent building inspectors. 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], point out that construction defects are a common problem in housing provisions in Malaysia. Theoretically, new homes should be free from defects. To verify the quality of the apartments being built, buildings should be inspected from the early stages of construction until the handover stage. Defects are identified and classified by defect type, and the overall results indicate that most common construction defects in new homes are cosmetic. These defects are mainly due to poor workmanship. To mitigate this problem, developers must ensure that contractors are qualified, and that a thorough building inspection has been performed before handover of the home. [PERSON] and [PERSON] [1] studied defects in residential buildings in the Australian state of Victoria. 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. The analysis of selected articles indicates that defects in housing construction are common. They are located in various elements of buildings [11; 14], in regards to the structure and finish, and may affect the safety of use of apartments to varying degrees [12]. They are generated at various stages of the investment process, both during the design, construction, and operation of the facility [13; 17]. Defects in the building's structural elements should be identified in the earlier stages of construction because they are covered during the finishing works [1; 13]. By far the largest number of defects are cosmetic. Removing defects in residential buildings involves additional financial outlays.