# Atlas of Defects within a Global Building Inspection System
## 1 Introduction
### Expeditious Tools to Assess Building Pathology
Severity ratings of defects are also used in research about a decision-making process to select facade materials minimising potential defects at the design stage [60]. In this situation, severity ratings are used to determine the criticality of defects according to a five-point scale, where the seriousness of defects is assessed. These severity ratings are as follows: extremely minor (1), minor (2), moderate (3), major (4) and extremely major (5). Another scale determines the frequency rating of defects. [PERSON] and [PERSON] [61] developed a building inspection system for evaluating the technical performance of existing buildings. The third step of that system includes the assessment of the severity of defects using a severity rating associated with the effects of defects and with their urgency of repair. Three levels of severity are determined according to general criteria: severity 1 refers to low impact, severity 2 to moderate impact and severity 3 to severe impact. The assessment results are used to support maintenance recommendations. The set of individual expert inspection systems developed by the authors' research team at IST-UL includes, in each detailed file of defects, the classification parameters to determine the severity/repair urgency level of each detected defect. These parameters are used to rate defects from level 0 to level 2. Level 0 corresponds to the need for immediate intervention, level 1 to the need for intervention in the medium term, and level 2 to the need for monitoring the progression of the defect. When the set of individual inspection systems was used to develop the global inspection system, where the atlas of defects was included, the three levels were adapted to a five-level scale, considering implicit gravity differences between different building elements/materials, i.e., the effects of defects may be aggravated by the characteristics of some materials. Furthermore, the global inspection system was developed in conjunction with service life prediction models for the same scope of building elements/materials [62]. Those models already included a methodology to determine the severity of degradation of building elements. For this reason, in the global building inspection system, the rating of defects was restricted to the urgency of repair [11]. At IST-UL, a research team has been developing service life prediction methodologies for elements/materials of the building envelope [62]. Those methodologies start by determining the following: the weighted severity of degradation of building elements (%) according to the area of the building element affected by each defect; that defect's multiplying factor as a function of its condition (from 0 to 4); and the type of defect's weighting coefficient, which corresponds to the relative importance of each defect. The obtained severity of degradation is then placed on a discrete scale that qualitatively defines the degradation level. So, two different scales are used: (i) one to determine the detected defects' multiplying factor according to its condition, varying from 0 to 4, where 0 correspond to very slight degradation and 4 to severe degradation; and (ii) another to define the building elements' degradation level, varying from no visible degradation (level A) to generalised degradation (level E), matching percentages of severity of degradation. [PERSON] et al. [9] studied the optimal metric for condition rating scales. This study tested a representative group of experts on how they would classify 33 different cases of building pathology in building elements through direct assignment, according to a proposed scale with 11 levels of severity. The statistical analysis of the answers allowed determining that the proposed scale needed improvement since only a 32% probability of correct classification of the phenomena was achieved. Using a clustering algorithm, a five-level scale was determined to provide the lowest standard deviation of the global error. IST-UL's global inspection system also proposes five levels of urgency of repair.