Fixing and buying guide

What this product is and who needs it

This insulation collar is an essential component for anyone installing a CK04 VELUX roof window in a timber-framed loft. It creates a thermally efficient seal around the window frame opening, minimising heat loss and draughts. If you are upgrading your loft insulation or installing a new roof window, this collar helps prevent thermal bridging at the window perimeter, which is particularly important in UK buildings where loft heat loss is a significant factor in overall home energy efficiency.

Compatibility and sizing

This collar is sized at 55 x 98cm and is compatible only with CK04 VELUX roof windows. Before ordering, confirm that your roof window is a CK04 model. The collar is designed for timber-frame construction, so it is suitable for standard timber loft structures. Do not use this collar with other VELUX window sizes or frame types, as it will not fit correctly and will not provide the intended thermal performance.

What is included and pre-installation checks

The collar is supplied as a single unit ready for fitting. Before installation, ensure that your CK04 roof window is to hand and that the opening dimensions match the collar size. Check that your loft frame is timber construction and that the opening is clean and free from debris. Verify that you have adequate access and headroom to fit the collar around the window frame during installation.

• Confirm CK04 window model compatibility
• Check timber-frame construction of your loft
• Ensure opening is clean and clear of obstructions
• Have the roof window ready for concurrent installation

Installation and performance

The insulation collar is fitted around the window frame opening as part of the roof window installation process. Its fiberglass construction with baked enamel finish provides durability and straightforward handling during fitting. The collar creates a snug fit that minimises heat loss and air leakage, contributing to improved loft thermal performance. Once fitted correctly, it requires no further adjustment or maintenance and will perform reliably in standard UK loft conditions.