# Atlas of Defects within a Global Building Inspection System
## 4 Discussion
If the affected areas are of medium aesthetical value and larger than 20% of the rendered surface, they should be classified within level 2 of urgency of repair. Figure 6c,e occur on side facades, thus having medium aesthetical value, but only the affected area of Figure 6e represents more than 20% of the rendered surface (about 58%). So, Figure 6e requires intervention in the short-term (level 2). The remaining situations, i.e., Figure 6b,c, are of level 3 of urgency of repair, as their characteristics do not match any of the parameters defined for levels 1 and 2. Summing up, the urgency of repair of cases in Figure 6 is as follows:  
* Figure 6a: level 1;
* Figure 6b: level 3;
* Figure 6c: level 3;
* Figure 6d: level 1;
* Figure 6e: level 2;  
Figure 5: Cases of defect “A-A3 Dirt and accumulation of debris” in window frames: (**a**) accumulation of debris affecting the operation of moveable leaves and obstructing drainage holes; (**b**) dirt in a window frame on a front facade; (**c**) dirt in a window frame on a rear facade. Once again, the criterion associated with the aesthetical value of the affected areas is decisive. For instance, Figure 6c,f have identical characteristics, but the importance of Figure 6f, showing the front facade, which is adjacent to the public street and forms a uniform set of facades that frames that street, determines that, when prioritising the repairs, this case should be repaired first. The analysis of [PERSON] et al. [65] of the damage of old mortars systematises the factors affecting the mortars' degradation processes. Of those, some may be highlighted for affecting the development of \"Dirt and accumulation of debris\" (A-A3) in the cases shown in Figure 6. In terms of environmental factors, the moisture supply and the air pollution impact all the mentioned cases. Furthermore, the moisture supply, in these cases, is associated with rain runoff and surface water. In Figure 6c,f, the effect of rainwater runoff is more evident as no coping/capping stone/flashing is observed on the top of the rendered surfaces. As wet-dry cycles occur successively, different types of dirt particles tend to accumulate on the wet surface of the rendered facade [66]. So, a design factor is also associated with these cases of degradation (detailing of the building) [65]. On the other hand, in Figure 6a, the differential washing effect of rainwater affects the facade below windowsills. When rainwater reaches a facade, the water flow over the surface carries dirt particles, washing them off. Some areas of the facade are not affected by this phenomenon and keep accumulating dirt [66]. Moreover, in Figure 6d,e, dirt accumulates on areas where water condensation occurs. This is called a thermophoresis phenomenon, which is associated with poor thermal insulation conditions [67]. Additionally, the lack of maintenance and the properties of the mortar system may affect the degradation processes in Figure 6. The porosity of materials may also affect the accumulation of dirt on the facades [65]. Figure 6: Cases of defect “A-A3 Dirt and accumulation of debris” on wall renders: (a) dirt below windowsills on a front facade, (b) dirt on a rear facade, (c) dirt on a side facade, (d) dirt on a rear facade, (e) dirt on a side facade, (f) dirt on a front facade. Looking now at instances of defect \"A-C2 Oriented cracking on the current surface\", Figure 7 shows four situations of oriented cracking on architectural concrete surfaces. Analysing the criteria to define the urgency of repair, in Figure 4, the main classification parameter is the average crack width. Although a crack width ruler was not used in the photographs in Figure 7, due to the elevated position and consequent lack of access to the cracks within the facades, other elements may be considered as size references, such as bug holes, fastening marks or panel/casting joints.