Fixing and buying guide

Who this product is for

This collar is essential for builders, roofers, and serious DIY installers fitting VELUX roof windows or wall-mounted roof lights. It is particularly important in new builds and renovation projects where thermal performance and moisture control are priorities. Use it whenever you are installing a VELUX window into timber-framed roof or wall structures.

Compatibility and sizing

Before ordering, confirm that your timber structural members are graded F16, F24, or F32. The collar dimensions are 134 x 140cm (52 x 55 inches). Check your VELUX window or roof light specification and the opening dimensions in your roof or wall structure to ensure this size matches your installation requirements. Measure the opening carefully and cross-reference against your VELUX product documentation.

• Compatible with timber grades F16, F24, and F32 only
• Size: 134 x 140cm — confirm this matches your opening before purchase
• Designed for use with VELUX insulation boards
• Suitable for both pitched roof and vertical wall applications

What is included and material

The collar is manufactured from fiberglass with a baked enamel coating for durability and moisture resistance. The baked enamel finish protects the fiberglass and helps prevent water ingress at the critical junction between the window frame and the building structure. One collar per pack is supplied at the dimensions stated.

• Material: Fiberglass with baked enamel coating
• Quantity: One collar per pack
• Finish: Baked enamel for weather and moisture protection

Pre-installation checks and fixing

Before installation, inspect the opening in your roof or wall structure to ensure it is square and the correct size for this collar. The collar must sit flush against the timber frame with no gaps. Use suitable fixings appropriate to your timber grade and the collar material — your VELUX documentation will specify recommended fixings. Install the collar in line with the window frame, ensuring the baked enamel coating faces outward to shed water. Always follow VELUX installation instructions and building regulations for your application. The collar works most effectively when used alongside VELUX insulation boards to create a complete thermal and moisture barrier.

• Check opening dimensions match the 134 x 140cm collar size
• Ensure the opening is square and the timber frame is level
• Use fixings suitable for your timber grade — consult VELUX guidance
• Install with baked enamel coating facing outward
• Use in conjunction with VELUX insulation boards for best performance
• Follow VELUX installation instructions and local building regulations