The long-term durability of polyurethane waterproofing membranes with top coating layers was evaluated through static and dynamic outdoor exposure tests. No cracks appeared under static conditions, while dynamic tests produced cracks originating both at the membrane bottom above substrate joints and at the top-coating surface. Crack initiation time in the top coating depended mainly on polyurethane thickness and joint movement. A mathematical model describing this relationship was developed, and FEM analysis was conducted to identify crack initiation locations.
