# Vulnerability of Buildings to Meteorological Hazards:
## 2 Materials and Methods
### The Selection of Indicators
#### 2.2.2 Indicators for Heavy Rain  
Heavy rain may damage different parts of the building. The following indicators were selected for consideration in this study based on the damage pattern descriptions in the literature [23] (Table 1):  
_Rood slope:_ The slope angle of the roof is one of the most important vulnerability indicators when it comes to heavy rainfall. In more detail, flatter roofs experience frequent damage by heavy rainfall as the water remains on the roof and the runoff is not fast, so the possibility of infiltrating into roof components increases [45].  
_Presence and length of the overhang:_ [PERSON] et al. [46] have shown that there is a significant reduction in the amount of wind-driven rain deposition on the upper half of the facade due to roof overhangs. A survey implemented by [PERSON] and [PERSON] [47] showed that a low-rise building with a typical overhang of 0.3-0.6 m and a 12-story high-rise building with a typical overhang of 0.9 m can significantly reduce the deposition of wind-driven rain on the building.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Indictors** & **Windstorm** & **Heavy Rainfall** & **Hall** \\ \hline Roof shape & ✓ & ✓ & ✓ \\ \hline Roof material & ✓ & ✓ & ✓ \\ \hline Roof slope & ✓ & ✓ & \\ \hline Overhang length & ✓ & ✓ & ✓ \\ \hline Number of floors & ✓ & & ✓ \\ \hline Glazing type of window & ✓ & ✓ & ✓ \\ \hline Presence and type of shutter & ✓ & & ✓ \\ \hline Engineering-based state of the building & ✓ & & \\ \hline State of non-structural elements & ✓ & & ✓ \\ \hline Presence and state of the balcony & ✓ & ✓ & ✓ \\ \hline Presence and state of the basement & & ✓ & \\ \hline Presence and state of the gutter & & ✓ & \\ \hline Presence and state of the intersections’ waterproofing & ✓ & & \\ \hline \end{tabular}
\end{table}
Table 1: Vulnerability indicators and their relevance to different meteorological hazard types.  
_Rool material_: Damage can take place in the interior of the building due to roof leakages and for this reason, the material of the roof has to be considered in a vulnerability analysis [48]. _Rool shape_: The shape of the roof is also of great importance and should be considered since it may or may not favor the accumulation of water on top of the building.  
_Window glazing_: Infiltration through windows and doors is possible and for this reason sealing is important [49]. The window glazing, however, may be a decisive factor when the building is exposed to wind-driven rain [50].  
_Presence and state of the balcony_: The balcony may be a surface that enables the accumulation of water. As such, it may favor infiltration in the interior of the building through openings (windows, balcony doors that are not sealed). However, the balcony itself may also be damaged by heavy rain. [PERSON] et al. [23] suggest that in Germany, damage to balconies and their connections to the external walls of the building has been recorded after heavy precipitation events. In Germany, the same regulations that apply for flat roofs also apply to balconies [23].  
_Presence and state of basement_: Heavy rain may be responsible for some pluvial flooding, which in this case would directly affect the basement of the building. Indirectly, apart from water damage in the basement (floors and walls), electrical installations that are located there and are significant for the functionality of the building may also be damaged [49].  
_Presence and state of the gutter_: The presence, condition, and size of gutters are of major importance. Accumulated water on surfaces such as roofs and terraces has to be able to flow away [49].  
_Presence and state of the intersections' waterproofing_: Intersections of the roof, such as chimneys, vents, dormers, cullies, and coverings, are particularly vulnerable to the impact of heavy rainfall [45].