To limit the probability that performance will fall significantly below expectations with respect to substrate preparation, protective separation sheets, application of PVC membrane, membrane flashing and inspection, which could lead to premature failure, which could lead to precipitation or meltwater ingress, which could lead to water penetrating directly to roof decking or sheathing, which could lead to deterioration, which could lead to the structural failure of roofs or assemblies protected by roofs, which could lead to harm to persons.