Fixing and buying guide

What this product is and who needs it

This is a roof flashing specifically engineered for VELUX roof windows and Sun Tunnel systems. It sits between the roof material and the window frame, creating a weather-tight seal that prevents water ingress around the roof penetration. Builders, roofers, and serious DIY installers use this flashing when fitting VELUX roof windows to ensure a professional finish and long-term weather protection. It is essential for both new roof installations and refurbishment work where existing roof windows are being replaced or upgraded.

Compatibility and sizing

This flashing is sized at 550 x 780mm (55 x 78cm) and is compatible with standard VELUX roof window ranges. The 18mm slate gap specification means it is designed for use on slate roofs. Before ordering, confirm that your VELUX roof window model matches this flashing size and that your roof material is slate or compatible with the 18mm gap specification. Check your window documentation or contact VELUX directly if you are unsure of the correct flashing size for your installation.

• Dimensions: 550 x 780mm
• Slate gap: 18mm
• Material: Aluminium with weather-tight sealing
• Compatible with standard VELUX roof window systems

Pre-installation checks

Before fitting, inspect the flashing for any damage or defects. Ensure your roof opening is cut to the correct size and that the surrounding roof structure is sound and level. Check that all necessary VELUX window components are to hand, including the window frame itself and any additional sealing strips or accessories specified by VELUX for your particular installation. Verify that your roof material and pitch are suitable for the 18mm slate gap specification of this flashing.

• Check flashing for damage before installation
• Confirm roof opening dimensions match the 550 x 780mm flashing size
• Ensure roof structure is level and sound
• Verify slate roof compatibility with 18mm gap specification

Installation and finish

This flashing forms part of a complete VELUX roof window installation system. It must be fitted in conjunction with the compatible VELUX roof window frame and any additional sealing components specified by the manufacturer. The aluminium construction with weather-tight sealing ensures reliable performance in UK roof conditions. Professional installation is recommended to guarantee a weather-tight seal and neat roof finish. Refer to VELUX installation instructions for detailed fitting procedures specific to your window model and roof type.