Fireproofing and Sealing Methods for Vertical Shaft Cable Trays

Effective fireproof sealing for vertical shaft cable trays requires modular firestop systems, fire-resistant mineral wool, intumescent caulks, and proper installation to prevent fire and smoke spread.

Key Considerations

Fireproof sealing in vertical cable shafts is critical to prevent the rapid spread of fire and smoke, especially in high-rise buildings where the chimney effect can accelerate fire propagation . Openings around cable trays must be tightly sealed, with no visible cracks or voids, and gaps should not exceed 1 cm² . Large openings may require fire-resistant backing plates or support plates to ensure structural integrity and fire resistance.

Recommended Materials

• Firestop Packs and Mineral Wool: Fire-resistant mineral wool or firestop packs are commonly used to fill gaps around cables and trays. Packing thickness should be sufficient (typically ≥24 cm) to maintain fire integrity .
• Intumescent Caulks: Products like IC 15WB Caulk expand under heat to seal gaps and prevent smoke and flame penetration .
• Modular Firestop Systems: Systems such as FIRSTO provide modular, easy-to-install solutions for multi-cable and cable tray penetrations. They allow for later cable additions or removals while maintaining fire and smoke protection .
• Fire-Resistant Boards and Coatings: Fire-rated boards or coatings, such as KBS® Foamcoat, can be applied to maintain temperature limits on steel trays and prevent fire spread .

Installation Guidelines

1. Prepare the Shaft: Ensure floor and wall finishes are complete, and shaft doors are installed .
2. Install Backing Plates: For large openings, place fire-resistant backing plates before sealing.
3. Pack and Seal: Insert firestop packs or mineral wool around cables and trays in an orderly sequence, ensuring all gaps are sealed internally and externally .
4. Apply Caulk or Coating: Use intumescent caulks or coatings to cover edges and complete the seal.
5. Cover Plates: Install square, evenly painted cover plates to close the opening and maintain aesthetics .
6. Compliance and Testing: Ensure the system meets local fire codes and has been tested for thermal insulation, smoke sealing, and mechanical load resistance .

Performance Considerations

The effectiveness of a fireproof sealing system depends not only on the material but also on the construction process. Proper installation ensures thermal insulation, smoke containment, and overall integrity during fire events . Modular systems like FIRSTO provide flexibility, high mechanical load resistance, and ease of maintenance, making them suitable for vertical shaft applications . By combining fire-resistant materials, modular systems, and proper installation, vertical shaft cable trays can achieve reliable fireproof sealing that meets building code requirements and enhances occupant safety.