How and where to use guide
VELUX Insulation Collar 94x140cm BDX PK08 2011
Where to use this product
Install the VELUX Insulation Collar in loft conversions and new build properties where PK08 roof windows are being fitted. The collar is positioned around the roof truss opening, creating a thermal and moisture barrier between the window frame and the structural timber. It is suitable for use with timber grades up to BDX PK08 2011. Always verify that your roof truss timber grade matches or is lower than the specified grade before installation. The 94 x 140cm size is designed specifically for PK08 window openings.
- Loft conversions with new or replacement roof windows
- New build properties with roof window installations
- Any project requiring thermal insulation around roof window frames
- Timber structures graded BDX PK08 2011 or lower
Installation and application
Position the fiberglass collar around the roof truss opening before or during window installation. The collar should sit flush against the timber frame, creating a continuous seal with no gaps. Ensure the collar is centred around the opening and secured firmly to prevent movement during construction work. The fiberglass material is flexible enough to accommodate minor variations in truss dimensions but should not be stretched or compressed excessively. Follow VELUX manufacturer guidance and current site practice for your specific window model to ensure correct positioning and fixings.
- Measure the opening and confirm dimensions match 94 x 140cm specification
- Position collar around truss before window frame installation where possible
- Ensure collar sits evenly and creates a complete seal around the opening
- Secure with appropriate fixings suitable for both fiberglass and timber
- Check for gaps and compress gently to achieve snug fit
Performance benefits and limitations
The collar significantly reduces heat loss at the roof window junction, improving overall loft space thermal performance and reducing heating costs. It also helps prevent condensation forming on internal surfaces around the window frame by maintaining warmer temperatures at the timber interface. However, the collar is only effective when installed correctly with no gaps or compressions that would compromise the seal. It does not replace the need for adequate ventilation in the loft space or proper vapour control measures elsewhere in the roof structure. Performance depends on correct installation in line with manufacturer specifications.
- Reduces thermal bridging at roof window installation point
- Minimises condensation risk in loft spaces
- Improves energy efficiency when installed as part of complete thermal strategy
- Does not substitute for adequate loft ventilation or vapour barriers
- Effectiveness depends on correct installation without gaps or damage
Maintenance and on-site handling
Inspect the collar during and after installation to ensure it remains in position and undamaged. The fiberglass material is durable but can be damaged by sharp tools or rough handling on site. Protect the collar from damage during subsequent construction work, particularly when installing insulation batts or boarding around the window. Once the loft space is fully finished, the collar requires no ongoing maintenance. If damage is identified before the window is fully sealed, replace the collar to maintain thermal and moisture performance.
- Handle carefully to avoid tears or compression damage
- Protect from damage during insulation and boarding installation
- Inspect before sealing the window frame to confirm correct position
- No routine maintenance required once installation is complete
- Replace if damaged before final sealing to maintain performance