The paper deals with crack nucleation and propagation caused by time-dependent process of deterioration in creep conditions. Three distinctive stages of the damage growth in a rectangular plate subjected to uniform pressure load are considered: nucleation in a point, propagation through the plate thickness, and development of critical network of the cracks bringing a structure to the final collapse. With corresponding times denoted by t1, t2 , and t3, their relationships had been evaluated to indicate the safety margins throughout the whole process. Spatial configuration of crack networks, including their profiles and branching, is shown as time-dependent process, which leads to the structure collapse caused by the loss of kinematical stability.