Distance for sealing cable trays with fireproof putty

Cable tray penetrations should be sealed tightly with fireproof putty, ensuring gaps around cables do not exceed 1 cm² and all voids are fully filled.Key Guidelines for Fireproof Putty Application

Gap Size and Spacing: When sealing cable trays passing through walls, floors, or shafts, the gap between the firestop material and cables should not exceed 1 cm², and the packing thickness should be at least 24 cm for large openings . All gaps inside and around metal trunking must be sealed completely, both internally and externally, to prevent fire and smoke spread . Firestop Material Selection: Use appropriate fireproof materials such as firestop putty, firestop mastic, fire-resistant mineral wool, or fire-rated boards. Putty-based solutions like 3M Fire Barrier Moldable Putty+ or ROCKWOOL FirePro® SpeedSeal are designed for cable penetrations and can accommodate multiple cables while maintaining fire resistance . Installation Considerations:

• Ensure the floor and wall finishes are completed and shaft doors are installed before sealing .
• For large openings, install a fire-resistant backing plate before applying putty .
• Firestop putty should be applied without visible cracks or voids, fully encapsulating the cables and filling all gaps .
• Cover plates should be square, evenly painted, and properly dimensioned to close the opening securely . Maintenance and Inspection: Periodically inspect sealed cable trays to ensure the putty remains intact, with no shrinkage, cracks, or gaps that could compromise fire protection . Summary: Proper firestopping requires tight, continuous sealing around cable trays, with gaps not exceeding 1 cm², sufficient packing thickness, and the use of tested fireproof putty or equivalent materials. Following these guidelines ensures compliance with fire safety standards and effective containment of fire and smoke.