Among the factors that mostly influence the damage of ancient masonry structures, viscous sliding and creep-fatigue interaction are among those that worth mentioning; in particular, persistent heavy loads have proved to be the cause of a continuous and slow damage. The problem of obtaining a reliable estimate of the service life of historical masonry buildings towards the effects of persistent load involves many uncertainties, therefore it can conveniently be treated with a probabilistic method. The proposed stochastic approach is rather simple and finds its basis in that proposed in the previous chapter for the evaluation of the durability of stone material over time. In this chapter, the results of laboratory pseudo-creep tests on ancien...