Deterioration prediction of Civil Infrastructure from discrete condition data is a challenge faced by many asset managers developing effective maintenance and renewal strategies. Due to high variability of data, often, deterministic methods are not readily applicable. Some of the reliability based methods adopted are time dependent reliability analysis, Markov process and more recently Gammas process. Whilst such models have been developed for assets with smaller number components, such as bridges and storm water pipes, for complex systems such as buildings reliability based methods are less common.