Fixing and buying guide

Who this product is for

This insulation collar suits builders, roofers, and serious DIY customers undertaking loft conversions or new build work with VELUX PK08 roof windows. It is particularly valuable where condensation has been a concern or where building regulations require enhanced thermal performance around roof penetrations. If you are installing a PK08 window into timber roof trusses and want to minimise heat loss and moisture problems, this collar is a practical addition to your specification.

Compatibility and sizing

This collar is sized at 94 x 140cm and is designed specifically for VELUX PK08 roof windows installed in timber graded to BDX PK08 2011 or lower. Before ordering, confirm that your roof window model is PK08 and that your timber grade matches or is lower than BDX PK08 2011. Measure your roof truss opening to ensure the collar dimensions will fit your installation. If your window size or timber specification differs, check the product specification carefully or contact the supplier to avoid ordering an incompatible item.

What is included and pre-installation checks

You will receive one fiberglass insulation collar sized 94 x 140cm. Before installation, inspect the collar for any damage in transit. Confirm that your roof window frame and truss opening match the stated dimensions and that the timber grade is compatible. Check that the roof structure is sound, dry, and ready to receive the collar. Ensure you have adequate working space around the roof window opening and that you are familiar with the current site practice and VELUX manufacturer guidance for collar installation.

• Inspect collar for transit damage before fixing
• Verify PK08 window model and BDX PK08 2011 timber grade compatibility
• Measure roof truss opening against 94 x 140cm collar dimensions
• Confirm roof structure is sound and dry

Installation and performance

The collar fits securely around the roof truss at the point where the window penetrates the roof structure. It creates a thermal and moisture barrier that reduces heat loss through the installation and helps prevent condensation forming in the loft space. Install in line with VELUX manufacturer guidance and current best practice for your project type. Proper installation is essential to achieve the thermal and condensation-prevention benefits. If you are unsure about installation method or positioning, refer to the manufacturer's instructions or seek guidance from an experienced roofer.

• Reduces heat loss around the window installation
• Helps prevent condensation in loft spaces
• Provides secure fit around timber roof trusses
• Install following VELUX guidance and site best practice