Sealing the cable trays on the roof

Cable trays passing through roofs must be sealed using weatherproof service risers, specialized roof penetration fittings, and durable sealants to ensure watertight, windproof, and structurally sound installations.

Key Considerations

Weatherproofing: Roof penetrations are vulnerable to water ingress, wind, and environmental exposure. Proper sealing prevents leaks, protects cables, and maintains the integrity of the building envelope while keeping out birds, rodents, and insects . Structural Support: Penetrations must be supported to handle the weight of the cable tray and resist movement caused by wind or thermal expansion. Upstands or risers are often used to provide this support . Fire Safety: Sealing systems should maintain fire barriers where required, especially in commercial or industrial buildings .

Recommended Methods

1. Service Risers and Roof Penetration Fittings: For roof penetrations, service risers or specialized fittings like the ROOFPORT® system provide a weatherproof entry point for cables. These systems integrate with the roof membrane and often include removable cowls for future cable additions .
2. Sealing Inserts and Flanges: Products such as the KRASO Flat Roof Penetration use a sealing insert combined with a foil clamping flange. These are oil- and bitumen-resistant, UV-protected, and can be swivelled 360° to accommodate cable routing. They are compatible with various roof membranes like EPDM, FPO, and RESITRIX® .
3. Sealants: High-quality, permanently elastic sealants such as PU-based sealants or GRP weathering systems are applied around the cable tray and penetration point to ensure a watertight and durable seal. These sealants can often be applied on moist surfaces and provide long-term protection .
4. Weatherstop Systems: For larger or multiple cable trays, weatherstop frames with water-resistant pads and silicone-based sealants can be used. These frames encompass the tray at the penetration point and are suitable for outdoor and wet environments, allowing easy maintenance and cable changes .

Installation Best Practices

• Plan the Entry Point: Choose a location that minimizes cable bends and avoids structural obstacles. Ensure accessibility for installation and future maintenance .
• Drill at a Slight Downward Angle: This helps prevent water pooling and facilitates drainage .
• Integrate with Roof Membrane: Ensure the penetration system is fully bonded or clamped to the roofing material to maintain waterproofing .
• Check Local Codes: Comply with building regulations regarding fire safety, waterproofing, and structural integrity . By combining service risers, specialized penetration fittings, and high-quality sealants, cable trays can be safely routed through roofs while maintaining weatherproofing, structural support, and fire safety.