# Atlas of Defects within a Global Building Inspection System
## 4 Discussion
Two criteria have to be met to include an oriented cracking phenomenon in architectural concrete surfaces in the level 1 set (need for immediate intervention): (i) the average crack width must be 0.8 mm or wider, and (ii) the defect must have conditions to progress. Considering that the exposure conditions of all cases in Figure 7 remain unchanged, all cases meet the second criterion. As for the crack width, Figure 7a,b show clearly wider cracks than Figure 7c,d. Therefore, the former should be accounted for as level 1 of urgency of repair. A-C2 occurrences in architectural concrete surfaces belong to level 2 of urgency of repair when the average crack width is greater than 0.2 mm (and thinner than 0.8 mm). Careful analysis of Figure 7c,d allows discovering some differences between them, the most important being that the crack in Figure 7c is better defined throughout its length, while the crack in Figure 7d almost disappears in some places. Although the analysis of the threshold is not very precise and is more comparative in nature, given the provided data, Figure 7c should be rated as level 2 and Figure 7d as level 3 of urgency of repair. Figure 7: Cases of defect “A-C2 Oriented cracking on the current surface” in architectural concrete surfaces. Figure 7a-d all show different cases of defect \"A-C2 Oriented cracking on the current surface\" in architectural concrete surfaces. As the explanation would be the same for all, only a general explanation was provided. The National Precast Concrete Association [68] also suggests thresholds to classify the width of cracks on architectural concrete. Three types of cracks are proposed--fine, medium and wide--with the following width ranges (original values are provided in inches): fine cracks are less than 0.25 mm wide, medium cracks are between 0.25 mm and 1.01 mm wide and wide cracks are more than 1.01 mm wide. This classification is only slightly different from that proposed in Figure 4, not changing significantly the assessment of cracking phenomena in Figure 7.  
In Figure 8, three different cases of \"Oriented cracking on the current surface\" (A-C2) on adhesive ceramic tiling are observed. These cases may be rated according to the levels of urgency of repair defined in the atlas of defects (Figure 4); for adhesive ceramic tiling, only levels 2 and 3 are set for defect A-C2. Oriented cracking occurrences may be of level 2 of urgency of repair if one out of two conditions is observed: (i) simultaneous occurrence of leakage; or (ii) average crack width of 0.5 mm or greater. All the other occurrences are accounted for as level 3. Again, no crack width ruler was used to measure the cracks in Figure 8, but the size of movement joints and other elements in the pictures may be used as a reference. Figure 8c shows almost imperceptible and very thin cracks. This occurrence does not meet any level 2 criteria, thus being classified as level 3 of urgency of repair. As for Figure 8a,b, Figure 8a appears to show wider cracking, but both cases present cracks wider than 0.5 mm. Additionally, Figure 8a also shows signs of leakage through the crack. Figure 8a-c all show different cases of defect \"A-C2 Oriented cracking on the current surface\" in adhesive ceramic tiling. As the explanation would be the same for all, only a general explanation was provided. Cracking phenomena in adhesive ceramic tiling are analysed by [PERSON] [69]. They may be caused by expansion and shrinkage phenomena affecting the bedding material and, consequently, the tile-mortar interface. The different coefficients of expansion of materials used in the substrate cause shear and tensile stresses that may cause failure. This may be the case in Figure 8a. Additionally, the significant width of the crack may cause water seepage, resulting in subsequent damage. The exercise of attributing an urgency-of-repair level to each case in Figures 5-8 may be extended to using other scales for comparison purposes. The methodological approach of [PERSON] et al.