Fire-rated assembly

Definition

The tested build recipe, identified by a design number, that a rated wall must reproduce exactly.

Why It Matters

The rating belongs to the assembly and not to the board, so a substituted screw pattern, a different stud gauge or a missed joint detail voids it, and the inspector checks the design number. A nonsymmetrical wall is tested from both faces and assigned the shorter of the two durations. Correcting a rated assembly after occupancy means opening finished walls, which is why this is a diligence question and not a punch-list one. Note it is an assembly design, not a product certification.