Fireproof sealing of cable tray openings in vertical shafts

Fireproof sealing of cable tray openings in vertical shafts requires a combination of approved firestop materials, proper installation techniques, and compliance with building codes to prevent fire and smoke spread.

Key Principles

Fireproof sealing in vertical shafts aims to contain fire and smoke within a compartment, preventing the chimney effect that can rapidly spread fire through cable shafts in high-rise buildings. The effectiveness depends on both the material properties and the installation process .

Common Fireproof Materials

1. Firestop Packs and Pillows: Modular, intumescent packs that expand under heat to seal gaps around cables and trays. They are suitable for retrofits and new installations .
2. Firestop Mastic and Caulk: Intumescent or latex-based sealants applied around cable trays to fill small gaps and ensure airtight sealing .
3. Fire-Rated Boards and Mineral Wool: Used for larger openings or as backing plates to support other firestop materials. Mineral wool provides thermal insulation and smoke sealing .
4. Modular Sealing Systems: Systems like Roxtec allow flexible, high-density cable entries and can accommodate future cable additions while maintaining fire integrity .

Installation Guidelines

• Sequence: Reserve openings → install cable trays → route cables → install firestop materials → apply cover plates if required .
• Gap Management: Ensure gaps between firestop packs and cables do not exceed 1 cm², and packing thickness meets minimum requirements (e.g., 24 cm for large openings), .
• Backing Plates: For large openings, install fire-resistant backing plates before sealing to maintain structural integrity and fire resistance .
• Layered Sealing: In high-rise shafts, consider interlayer or segmented sealing to prevent vertical fire spread .
• Cover Plates: Use square, consistent, and painted cover plates to close openings and protect the firestop system .

Performance Considerations

• Thermal and Smoke Resistance: Fireproof sealing systems must maintain integrity under high temperatures and prevent smoke diffusion .
• Compliance: Use UL-listed or nationally approved systems tested for the specific wall or slab type (e.g., concrete, gypsum) and fire rating .
• Maintenance and Flexibility: Modular systems allow cable additions or changes without compromising fire protection .

Recommended Practices

• Conduct a performance evaluation for the specific shaft configuration, considering cable density, shaft height, and potential fire load .
• Ensure tight, crack-free installation to maintain fire and smoke containment .
• Plan for future cable modifications using modular or flexible sealing solutions to avoid repeated structural penetrations . By combining approved firestop materials, proper installation, and compliance with standards, cable tray openings in vertical shafts can achieve effective fireproofing, minimizing the risk of fire and smoke propagation throughout the building .