How and where to use guide
VELUX Vapour Barrier 66x118cm BBX FK06 0000
Typical applications and installation location
The vapour barrier collar is positioned on the internal face of the roof structure, directly beneath the roof window or Sun Tunnel opening. It forms part of the weather-tight envelope by sealing the gap between the window frame and the roof construction. This component is essential in new build projects where vapour control is a building regulation requirement, and equally important in refurbishment work where existing roofs are being upgraded with new daylight or ventilation solutions. The collar ensures that warm, moist internal air cannot penetrate the roof structure and cause condensation or timber decay.
- Install on the internal (warm) side of the roof structure
- Position directly beneath the roof window or Sun Tunnel frame
- Use in conjunction with external flashing and weatherproofing components
- Suitable for pitched roof installations in residential and light commercial properties
Installation and on-site handling
Before installation, ensure the roof opening has been cut to the correct size and that the VELUX window or Sun Tunnel frame is positioned level and square. The vapour barrier collar should be carefully unrolled and positioned to fully cover the opening, with adequate overlap onto the surrounding roof structure. Secure the collar using the recommended fixings or adhesive as specified in the VELUX installation instructions for your particular window model. Take care to avoid puncturing or tearing the barrier material during handling and installation, as this will compromise its vapour-control performance. Ensure all seams and edges are properly sealed to maintain continuity of the vapour barrier across the roof penetration.
- Check window frame is level and square before fitting the collar
- Handle carefully to avoid damage to the barrier material
- Ensure full coverage of the roof opening with adequate overlap
- Seal all seams and edges according to VELUX instructions
- Do not install in wet or damp conditions; allow roof structure to dry if necessary
Limitations and maintenance
The vapour barrier collar is designed specifically for VELUX roof window and Sun Tunnel systems and should not be used with incompatible products. It is engineered for typical UK roof conditions but must be protected from mechanical damage during and after installation. Once installed, the collar requires no routine maintenance, but it should be inspected during any future roof work to ensure it remains intact and properly sealed. If the collar is damaged or punctured after installation, it should be repaired or replaced to maintain the vapour control function and prevent moisture-related problems in the roof structure.
- Use only with compatible VELUX roof windows and Sun Tunnel systems
- Protect from damage during construction and subsequent trades
- Check integrity if roof is disturbed for maintenance or repairs
- Replace if torn or punctured to maintain vapour barrier performance