Fixing and buying guide

What this product is and who needs it

This is a roof flashing designed to integrate VELUX roof windows or Sun Tunnel systems into slate-covered roofs. It is essential for any installer or property owner fitting or replacing a VELUX roof window or Sun Tunnel on a slate roof. The twin and combination design allows it to work with multiple window configurations, making it suitable for both single installations and more complex multi-window layouts.

Compatibility and sizing

This flashing is compatible exclusively with VELUX roof window and Sun Tunnel systems. The 550 x 1180mm dimensions (55 x 118cm) are fixed, so you must verify that your VELUX window or Sun Tunnel matches this size before ordering. The 8mm recessed slate design is engineered for standard UK slate roof coverings; check your roof slate thickness and profile to ensure compatibility. As a coupled flashing, it supports twin or combination window arrangements rather than single installations.

• Confirm your VELUX window or Sun Tunnel model matches the 550 x 1180mm size
• Verify your roof uses slate coverings with compatible profile and thickness
• Check that your installation requires a twin or combination flashing rather than a single flashing

What is included and pre-installation checks

You will receive one coupled recessed flashing unit. Before installation, inspect the flashing for any damage in transit and ensure all components are present. Check that the roof structure is sound, the slate covering is in good condition, and the opening for the VELUX window is correctly sized and positioned. Ensure you have the correct VELUX window or Sun Tunnel unit ready for fitting, along with any additional seals or fixings specified in the VELUX installation instructions.

• Inspect the flashing for transport damage before fixing
• Confirm the roof opening dimensions match the 550 x 1180mm flashing size
• Check that roof structure and slate covering are sound and suitable
• Have the VELUX window or Sun Tunnel unit and all associated fixings to hand

Installation and weather-tightness

The recessed 8mm slate design ensures the flashing sits neatly within the roof profile, creating a weather-tight seal that protects against water ingress. Follow the VELUX installation guidance carefully to ensure the flashing is correctly positioned and secured. Proper installation is critical to maintaining roof integrity and preventing leaks in UK weather conditions. If you are unsure about any aspect of the installation, consult the VELUX technical documentation or seek advice from a qualified roofer.