What is the primary purpose of a fire stop around penetrations in walls and floors?

• A. To seal around penetrations and prevent fire spread through openings
• B. To improve insulation against cold weather
• C. To guide electrical conduits through openings
• D. To provide a barrier for moisture only

Answer: (A)

Fire stops around penetrations are there to keep fire from moving through openings in walls and floors. When pipes, cables, or ducts pass through a barrier, gaps can become channels for flames, heat, and smoke, bypassing the fire-resistance rating of the assembly. Firestop materials—such as intumescent sealants, mortars, mineral wool, or collars—fill and seal those gaps so the barrier continues to resist fire even under heat. This maintains compartmentation, slows the spread of flames, and buys time for occupants and responders. It’s not primarily about cold insulation, guiding conduits, or moisture protection, even though those features may be incidental benefits.