How and where to use guide
VELUX Vapour Barrier 55x78cm BBX CK02 0000
Where to use this product
Install the vapour barrier collar on pitched roofs where VELUX roof windows or Sun Tunnels are being fitted. The collar sits at the roof penetration point, creating a seal between the window frame and the roof structure. It is compatible with standard VELUX roof window and Sun Tunnel ranges and works equally well in new build installations and refurbishment projects where existing roof coverings are being disturbed.
- Pitched roof installations with compatible VELUX roof windows
- VELUX Sun Tunnel systems requiring weather-tight sealing
- New build projects with standard roof construction
- Refurbishment work where roof penetrations need upgrading or replacing
Installation and application
The vapour barrier collar forms part of the complete VELUX installation sequence and must be fitted in conjunction with the window frame and flashing system. Position the collar around the roof window opening before the main flashing is installed, ensuring it sits flat against the roof structure. The collar creates a continuous vapour barrier that prevents warm, moist air from the interior penetrating the roof void, which could otherwise cause condensation and timber decay. Secure it according to VELUX installation instructions, which will specify fastening methods appropriate to your roof construction.
- Install as part of the complete VELUX window or Sun Tunnel system
- Position at the roof penetration point before main flashing installation
- Ensure full contact with roof structure for effective sealing
- Follow VELUX-supplied installation guidance for fastening and overlap requirements
Performance and maintenance
The collar is engineered to perform reliably in typical UK roof conditions, providing long-term weather protection and thermal efficiency. Once installed correctly, the vapour barrier requires minimal maintenance. Periodically check that the seal remains intact and that no gaps have developed around the perimeter, particularly after severe weather. Ensure that roof ventilation is not obstructed and that any condensation risk is managed through adequate loft ventilation, as the collar prevents vapour migration but does not replace proper roof void ventilation.
- Engineered for durability in UK climate conditions
- Check seal integrity annually, especially after high winds or heavy snow
- Maintain adequate roof void ventilation to prevent condensation buildup
- Do not use as a substitute for proper roof space ventilation design
Important limitations and on-site tips
This collar is designed specifically for compatible VELUX roof window and Sun Tunnel systems; do not attempt to use it with other manufacturers' products. The 550×780mm size is fixed, so verify compatibility with your specific VELUX model before ordering. Installation must follow VELUX technical guidance to ensure the weather-tight seal is achieved. Poor installation or use with incompatible systems will compromise weather protection and may lead to water ingress or condensation problems. Always refer to the VELUX installation manual supplied with your window or Sun Tunnel.
- Compatible only with standard VELUX roof window and Sun Tunnel ranges
- Verify product code CK02 0000 matches your VELUX system before installation
- Follow VELUX installation instructions precisely for weather-tight performance
- Do not attempt to modify or reuse if damaged during installation