A replacement membrane needs its own compatible details

A fictional building owner asks to substitute a different membrane during roof refurbishment. Its data sheet describes a similar intended exposure, so a purchaser assumes the old adhesive, drain accessories and joining method can all remain unchanged. The substrate condition and compatibility of the existing layers have not been checked. Another reviewer identifies that the proposal affects details already approved by the designer. There is no authorized installation procedure or live hot-work operation in this exercise. Explain why matching one general description is insufficient, what technical and contractual questions the substitution raises and how a documented decision can preserve the water-management and maintenance functions of the complete roof system.