Fire-stopping materials are used to seal penetrations of which fittings?

• A. Insulation materials for exterior walls.
• B. Sealants used to join ductwork.
• C. Materials for sealing metallic fittings.
• D. Nonmetallic fitting penetrations.

Answer: (D)

The main idea is that fire-stopping materials are used to preserve the fire-resistance of a wall, floor, or ceiling where something passes through it. In low-rise residential sprinkler work, these materials are applied around penetrations created by nonmetallic fittings—such as plastic sprinkler piping or plastic connectors—so that, if a fire occurs, flames and hot gases can’t travel through the opening. This helps maintain the rated integrity of the assembly. Insulation or duct-seal products aren’t designed to stop flame spread, and while metallic fittings may sometimes require protection, the standard focus for fire-stopping in this context is around nonmetallic fittings that pass through fire-rated assemblies.