ISO 15686 (ISO 2011) introduces the factor method for estimating service life of buildings and constructed assets. This method uses seven factors and argues that any one (or any combination) of these variables can affect the service life. The factors related to three main categories are considered, i.e., the inherent quality characteristics, environment, and operating conditions. Factor method suggests estimating the service life based on a reference service life, which is normally the expected service life in a well-defined set of in-use conditions that apply to the particular type of component (ISO 2012). The factor method is therefore expressed as shown in Fig. 1.