How and where to use guide
VELUX Insulation Collar 66x118cm BDX FK06 2011
Suitable applications and locations
This insulation collar is designed for use in pitched roof installations where VELUX roof windows are being fitted into timber-framed roof structures. It is suitable for new build projects, renovation work, and retrofit installations where energy efficiency and moisture control are priorities. The collar works effectively in all UK climate conditions and is particularly valuable in exposed locations where wind-driven rain and thermal bridging are concerns. It can be used in domestic and light commercial applications where the roof opening dimensions do not exceed 66cm wide by 118cm long.
- New build roof window installations
- Renovation and retrofit projects
- Timber-framed pitched roof structures
- Domestic and light commercial buildings
- Locations requiring enhanced thermal performance
Installation and preparation
Before installation, confirm that your timber roof structure is grade F18 or above, as this collar is not suitable for lower grades. The roof opening must not exceed the maximum dimensions of 66cm wide by 118cm long. Prepare the opening by ensuring it is square and level, with all rough edges removed. The collar should be positioned around the window frame perimeter before the window is fully secured, creating a continuous seal. Follow VELUX installation guidance to ensure the collar sits flush against both the window frame and the surrounding roof timber, with no gaps or compression that might compromise its sealing properties.
- Verify timber grade is F18 or above
- Check roof opening dimensions do not exceed 66×118cm
- Ensure opening edges are clean and free from splinters
- Position collar before final window fixing
- Maintain even contact around entire perimeter
Performance and maintenance
The fibre-reinforced polymer construction provides durable weather resistance and maintains its sealing properties throughout the life of the window installation. The collar prevents heat loss by eliminating thermal bridging at the window frame junction and blocks moisture ingress by creating a continuous barrier around the perimeter. After installation, inspect the collar periodically to ensure it remains in contact with both the window frame and roof structure, particularly after severe weather. The material requires no special maintenance beyond occasional visual inspection. If the collar becomes damaged or compressed, it should be replaced to maintain the thermal and moisture protection it provides.
- Inspect collar annually for damage or compression
- Check seal integrity after high winds or heavy rain
- Replace if damaged to maintain thermal performance
- No special cleaning or treatment required
- Maintains performance throughout window lifespan
Limitations and important considerations
This collar is designed specifically for roof windows with maximum opening dimensions of 66cm by 118cm. It is not suitable for timber grades below F18, as these do not provide adequate structural support and weather resistance. The collar creates a seal but does not replace proper roof flashing or weatherproofing around the window opening. Installation must follow VELUX guidance to ensure the collar functions correctly. Do not compress or stretch the collar excessively during installation, as this may reduce its effectiveness. The collar is designed for pitched roof applications and is not suitable for flat roof installations or vertical window openings.
- Maximum opening size 66×118cm only
- Timber grade F18 minimum requirement
- Must be used with proper roof flashing
- Follow VELUX installation instructions
- Not suitable for flat roofs or vertical windows