# Atlas of Defects within a Global Building Inspection System
## 1 Introduction
### Expeditious Tools to Assess Building Pathology
The proposed maintenance model includes three sets of metrics: the system condition index (SCI), the facility condition index (FCI) and the deferred maintenance cost estimate. Condition assessment ratings support the definition of SCI and FCI. A five-tier condition rating system is used, namely excellent (5), good (4), fair (3), poor (2), and bad (1). When a system does not exist, rating 0 is attributed. [PERSON] et al. [55] developed a visual survey methodology to assess the defects of the building envelope of social housing. Within this methodology, an evaluation scale was proposed, composed of eight degradation levels with specific parameters for each level according to the building element, taking the intensity, extent and location of damages into account. Level 10 is the most favourable degradation level, referring to an exceptional condition, not requiring any intervention, just planned maintenance actions for conservation purposes. Level 3 is the most severe degradation level, referring to an unacceptable condition, which is unsuitable for rehabilitation and requiring replacement. The survey methodology includes a step of aggregation of results for each type of building element. That aggregation considers the same scale, attributing a global degradation level according to the relative frequencies of degradation levels of each inspected building element. [PERSON] and [PERSON] [56] proposed using the severity of various deficiencies, defined by the surveyor on a scale from 0 to 100, to compute the overall deterioration index. That index also considers a weight attributed to each type of deficiency. The deterioration index is used to generate repair scenarios to optimise maintenance decisions, taking costs into account. [PERSON] et al. [57; 58] proposed methodologies to implement maintenance planning in pitched and flat roofs. Those methodologies encompass the establishment of intervention priorities for maintenance actions. In these studies, priorities are determined by the combination of four criteria: environmental aggressiveness of the surroundings, the extent of the defect, the level of deterioration of the building elements, and the severity of the defect. The last two criteria use two different scales, both for direct assignment. The degradation condition of the building elements is rated according to a four-level scale, ranging from 0 to 3, with the following definitions: no visible degradation (0), superficial degradation (1), moderate degradation (2) and generalised degradation (3). To determine the severity of the defects, a five-levels scale is used, from grades A to E, where A refers to \"negative influence on the aesthetical aspect\" and E to \"risk to the safety of users\". The combination of the different criteria is computed using weights and multiplying factors to determine a quantifiable intervention priority. The condition assessment method developed by the US Army Corps of Engineers [59] establishes two main types of assessment: detailed distress surveys and direct condition ratings. These methods are intended to be used in different scenarios, the latter being faster to use and the former more meticulous. While in detailed distress surveys the surveyor identifies each type of defect detected in a building component, when using direct condition ratings, the surveyor evaluates each component in more general terms. To measure the degradation in detailed distress surveys, each detected defect is classified according to severity levels (low, medium and high), whose criteria are defined for each type of defect in each type of building component. With direct condition ratings, the surveyor assesses each component according to a set of general rating criteria. Three main ratings are defined: green, amber and red, from little to serious serviceability loss due to degradation. Each rating is further subdivided into three categories: high (+), low (-) and middle. Both methodologies are used to compute condition indexes at different levels: component-section, building component, system and building.