Fixing and buying guide

What this product is and who needs it

This insulation collar is a purpose-made sealing component for VELUX MK06 roof windows with 78×118cm openings. It is required for anyone installing or upgrading loft insulation around a roof window, whether in new builds, conversions, or retrofit projects. The collar bridges the gap between the window frame and surrounding insulation material, preventing thermal bridging and draughts that would otherwise compromise building performance and comfort.

Compatibility and sizing

This collar is sized exclusively for MK06 windows with 78×118cm roof openings. Before ordering, confirm your window type and opening dimensions—using an incorrectly sized collar will result in poor fit and reduced thermal efficiency. The product is compatible with FSC-certified timber and above, which covers standard roof structures in UK residential buildings. Do not use with non-compliant or substandard timber framing.

• Window type: MK06 only
• Opening size: 78cm × 118cm
• Timber grade: FSC-certified and above
• Verify dimensions before purchase to avoid waste

Installation and pre-install checks

Installation must follow VELUX manufacturer guidance and current building practice to ensure thermal and structural performance. Before fitting, inspect the roof opening to confirm it matches the 78×118cm specification and that the surrounding timber is sound and properly graded. Ensure the roof structure is weather-tight and that any existing insulation or debris is cleared from the opening perimeter. The collar should be installed as part of a complete insulation strategy in accordance with Building Regulations and VELUX technical documentation.

• Verify opening dimensions match 78×118cm
• Check timber grade meets FSC-certified standard
• Clear opening perimeter of debris and old insulation
• Follow VELUX installation instructions precisely
• Ensure roof structure is weather-tight before installation

Pack contents and ordering

This product is supplied as a single insulation collar sized for one MK06 window opening. If you are installing multiple roof windows, order one collar per window. Check the product code BDXMK062000 matches your specification before checkout to confirm you have the correct size and window type.