How and where to use guide
VELUX Twin and Combination Flashings 55x78cm EKJ CK02 S0021E
Suitable applications and roof types
This flashing is designed for flat rooflights installed on pitched roofs with a maximum pitch of 30 degrees. It is compatible with timber-framed roof structures using joists of 28–32mm or 44–48mm thickness. The flashing works with standard roofing felt layers and is intended for use on residential and light commercial flat roof installations where a VELUX roofllight needs weatherproofing. The twin and combination design makes it adaptable to different flat roof configurations, including single and multiple roofllight installations.
- Roof pitch: up to 30 degrees maximum
- Timber joist thickness: 28–32mm or 44–48mm
- Roofing felt compatibility: standard 44–48mm felt systems
- Suitable for residential and light commercial flat roof applications
Installation and positioning
Install the flashing around the perimeter of the VELUX roofllight frame before laying the final roofing felt layer. Position the flashing so it sits flush against the roofllight frame and extends across the timber joists. The twin and combination design allows you to configure the flashing to suit your roof layout—typically one section acts as the primary weather barrier whilst the combination element provides additional flexibility at corners or where multiple rooflights meet. Ensure the flashing is fully seated and that all edges are secure before applying roofing felt over the top. The 4mm plastic construction is durable and will not degrade under normal roof conditions.
- Position flashing around roofllight frame before final felt layer
- Ensure full contact with timber joists and roofllight perimeter
- Use twin and combination sections to adapt to your roof layout
- Secure all edges before covering with roofing felt
Limitations and maintenance
This flashing is rated for roof pitches up to 30 degrees; do not use on steeper roofs as water run-off performance cannot be guaranteed. The flashing is designed specifically for the 55×78cm VELUX roofllight size—check your roofllight dimensions before ordering. Inspect the flashing annually, particularly after severe weather, to ensure the roofing felt seal remains intact and there are no gaps or lifting at the edges. Keep gutters and roof surfaces clear of debris to prevent water pooling around the flashing. The plastic material requires no special treatment but should not be exposed to direct sunlight for extended periods before installation, as this may affect flexibility.
- Maximum roof pitch 30 degrees—not suitable for steeper roofs
- Designed for 55×78cm VELUX rooflights only
- Inspect annually and after severe weather
- Keep roof clear of debris to prevent water pooling