What is the primary reason floor-to-wall systems are not acceptable for curtain walls?

The primary reason that floor-to-wall systems are not acceptable for curtain walls is tied to their testing parameters, which highlight the need for specific fire resistance capabilities in firestop systems. Floor-to-wall systems are typically evaluated based on their performance when tested between rated structures, which means they are designed to work within the framework of wall assemblies that have a specific fire-resistance rating.

Curtain walls, however, are often not constructed as part of an assembly that is rated for fire resistance; instead, they serve as non-structural facades. This mismatch means that the firestop systems used for floor-to-wall assemblies do not appropriately address the unique challenges presented by curtain walls, which are often exposed to different environmental conditions and fire risk scenarios.

Understanding this distinction is crucial for ensuring adequate fire safety and compliance with building codes, as the effectiveness of firestop systems is heavily influenced by their testing context and the structural aspects to which they are applied. Therefore, the testing conditions established for floor-to-wall systems do not translate to the needs of curtain wall systems, rendering them unsuitable for use in that context.