How and where to use guide
VELUX Twin and Combination Flashings 55x98cm EBL CK04 0021C
Typical applications and suitability
This flashing is intended for securing Velux roof vents on domestic and light commercial timber-framed pitched roofs. It works on roofs with pitches between approximately 15 and 30 degrees. The combination design means a single flashing can be configured to suit different roof layouts and vent positions, reducing the need to stock multiple flashing types. It is suitable for both new installations and replacement work on existing roofs.
- Domestic loft conversions and new roof vent installations
- Replacement flashings for existing Velux vents
- Roofs pitched between 15 and 30 degrees
- Timber-framed roofs with FSC 184 or equivalent timber grades
Installation and positioning
Position the flashing around the Velux vent opening before fixing to the roof structure. The twin and combination design allows you to configure the flashing to suit your specific roof layout. Ensure the flashing sits flush against the roof surface and the vent frame, creating a continuous seal. The 55x98cm dimensions are sized to accommodate standard Velux vent openings. Secure the flashing to the timber roof structure using appropriate fixings, ensuring all edges are sealed to prevent water ingress. Pay particular attention to the upper edge of the flashing, which must overlap the roof covering above the vent.
- Check roof pitch does not exceed 30 degrees before installation
- Position flashing centrally around the vent opening
- Ensure upper edge overlaps roof covering above the vent
- Seal all edges and fixings to prevent water penetration
- Use fixings suitable for both PVC and timber
Durability and maintenance
The UV-stabilised PVC construction resists weathering and maintains flexibility in temperature changes. Inspect the flashing annually, particularly after severe weather, to ensure the seal remains intact and no debris has accumulated around the edges. Clear any moss, leaves or dirt that may trap moisture. Check that all fixings remain secure and that the seal between the flashing and roof covering has not deteriorated. The PVC material does not require painting or coating, though the roof covering around it should be maintained according to its own specifications.
- Inspect annually for damage, cracks or seal deterioration
- Clear debris and moss from around the flashing edges
- Check all fixings remain tight and secure
- No painting or special treatment required for the PVC
- Replace immediately if the seal is compromised
Limitations and important notes
This flashing is rated for roof pitches up to 30 degrees only and should not be used on steeper roofs where water run-off may exceed the flashing capacity. It is designed specifically for use with Velux roof vents and timber-framed roofs compatible with FSC 184 timber grades. Do not use on flat roofs or roofs with inadequate pitch, as water pooling may occur. The flashing dimensions are fixed at 55x98cm and cannot be cut or modified without compromising the watertight seal.
- Not suitable for roofs pitched steeper than 30 degrees
- Designed for Velux vents only
- Do not cut or modify the flashing
- Not suitable for flat roofs or low-pitch applications
- Ensure timber grade compatibility before installation