Fixing and buying guide

What this product is and who needs it

The BBX vapour barrier collar is a specialist sealing component designed specifically for VELUX roof window and Sun Tunnel installations. It creates a weather-tight barrier that prevents moisture and air leakage around the window opening, protecting the roof structure and interior from water damage. This product is essential for builders, roofers, and serious DIY installers undertaking new build or refurbishment projects where VELUX roof windows or Sun Tunnels are being fitted.

Compatibility and sizing

This vapour barrier collar is engineered to work with compatible VELUX roof window and Sun Tunnel systems. The 940 × 1600mm dimensions are designed to fit standard roof window openings. Before ordering, confirm that your VELUX roof window or Sun Tunnel model is compatible with the BBX collar specification. Check your installation documentation or contact VELUX technical support if you are uncertain about compatibility with your specific product.

• Dimensions: 940 × 1600mm
• Designed for VELUX roof windows and Sun Tunnel systems
• Verify compatibility with your specific VELUX product before purchase

Pack contents and quantity

This product is supplied in a pack of 10 units. Each collar measures 940 × 1600mm. Consider the number of roof window or Sun Tunnel installations you are undertaking to determine how many packs you require. A single pack will cover 10 standard installations.

• Pack contains 10 vapour barrier collars
• Each unit measures 940 × 1600mm
• Order multiple packs if installing more than 10 windows or tunnels

Pre-installation checks and preparation

Before fitting the vapour barrier collar, ensure that the roof opening is prepared to the correct dimensions and that the surrounding roof structure is clean and dry. The collar must be installed as part of the complete VELUX roof window or Sun Tunnel system to achieve a proper weather-tight seal. Follow the installation instructions provided with your VELUX window or tunnel, positioning the vapour barrier collar at the correct stage of the build sequence. Proper installation is critical to prevent moisture ingress and ensure the longevity of your installation in UK roof conditions.

• Ensure roof opening is prepared to correct dimensions
• Check that surrounding roof structure is clean and dry
• Install as part of the complete VELUX system following manufacturer instructions
• Position at the correct stage of the installation sequence for weather-tight performance