What defines a membrane penetration?

A membrane penetration refers to an opening that only affects one side of a fire-resistance-rated assembly, such as a wall or floor. This definition is crucial in firestop applications because it emphasizes how fire-resistance features should be maintained in buildings. When there is a penetration in a membrane, such as for pipes or electrical conduits, it can compromise the fire-resistance integrity of that assembly.

Understanding the nature of membrane penetrations is critical for ensuring the appropriate firestop systems are installed. These systems are designed to seal such openings to restore the fire-resistance ratings and prevent the spread of fire and smoke. The other options address aspects that do not correctly align with the definition of a membrane penetration. For example, an opening that pierces the entire assembly (which would be a different type of penetration) does not maintain a clear distinction between the two sides, while options related to joints or openings without fire protection do not pertain to how penetrations through membranes affect the integrity of fire-rated assemblies.