Fixing and buying guide

What this product is and who needs it

The vapour barrier collar is a flashing component that sits at the point where your VELUX roof window or Sun Tunnel passes through the roof structure. It creates a weather-tight seal to stop rain and moisture reaching the roof deck and internal structure. You need this collar if you are installing a compatible VELUX roof window or Sun Tunnel system, whether in a new build property or during a refurbishment. It is not a standalone product and must be used as part of a complete VELUX installation.

Compatibility and sizing

This CK04 collar is sized at 550×980mm and is engineered specifically for VELUX roof window and Sun Tunnel systems. Before ordering, confirm that your VELUX product is compatible with the CK04 collar size. Check your VELUX installation documentation or product specification to verify the correct collar code for your window or tunnel model. Using the wrong collar size will compromise the weather-tight seal and may void warranty.

• Dimensions: 550×980mm
• Product code: CK04
• Compatible with VELUX roof windows and Sun Tunnel systems only
• Verify compatibility with your specific VELUX product before purchase

Pre-installation checks and preparation

Before fitting the collar, inspect the roof opening to ensure it is the correct size and that the surrounding roof structure is sound and level. Check that all VELUX window or Sun Tunnel components are on site and undamaged. The collar must be installed as part of the complete flashing system; do not attempt to use it independently. Ensure you have the correct installation instructions for your specific VELUX product, as collar fitting forms part of the wider roof penetration sequence.

• Confirm roof opening dimensions match the collar size
• Inspect roof structure for damage or movement
• Check all VELUX components are present and undamaged
• Have VELUX installation instructions to hand before starting work

Installation and professional finish

The vapour barrier collar is engineered to deliver a professional, visually consistent roof finish when installed correctly as part of your VELUX system. It works in conjunction with the window or tunnel frame and flashing to create a complete weather-tight seal. Follow the VELUX installation guide step by step, paying particular attention to the collar positioning and any sealant or fixings specified. Proper installation is essential to protect against moisture ingress and maintain the integrity of your roof in UK weather conditions.