Fixing and buying guide

What this product is and who needs it

This vapour barrier collar is a specialist component that sits between your VELUX roof window or Sun Tunnel and the roof structure. It prevents moisture and weather ingress around the window opening, which is critical in UK roof conditions where damp and condensation can compromise building performance. Builders, roofers, and serious DIY installers working on new builds or refurbishment projects will need this collar as part of a complete VELUX installation.

Compatibility and sizing

This collar is engineered specifically for VELUX roof window and Sun Tunnel systems. The 1140 × 1180mm dimensions correspond to the SK06 size category. Before ordering, confirm your VELUX window or Sun Tunnel model number and size designation to ensure this collar is the correct match for your installation. Using an incompatible collar will compromise the weather-tight seal and void performance guarantees.

• Check your VELUX product documentation for the correct collar size code (SK06)
• Verify window or Sun Tunnel model compatibility before purchase
• Do not substitute with collars from other manufacturers

Pre-installation checks and preparation

Inspect the collar for any damage before installation. Ensure the roof opening is cut to the correct dimensions and that the surrounding roof structure is sound and level. The collar must be fitted before the roof covering is installed to create a proper weather-tight seal. Have all VELUX installation instructions and flashing components to hand, as the collar works as part of a complete sealing system.

• Check collar for tears, creases, or manufacturing defects
• Confirm roof opening dimensions match the SK06 specification
• Ensure roof structure around opening is clean, dry, and level
• Gather all associated VELUX flashing and sealing components before starting work

Installation and professional finish

The vapour barrier collar must be positioned and secured according to VELUX installation guidance to ensure a weather-tight and visually consistent finish. Proper installation is essential for long-term roof performance and to prevent moisture ingress that could lead to structural damage or condensation issues. If you are unfamiliar with VELUX roof window installation, consider engaging a qualified installer to ensure the collar and window system are fitted correctly.