How and where to use guide
VELUX Twin and Combination Flashings 55x98cm EKN CK04 S0021E
Suitable applications and roof types
This flashing is specifically designed for slate roofs and is compatible with VELUX roof window and Sun Tunnel systems in the CK04 size range. It is suitable for use on both new build projects and existing properties undergoing refurbishment or retrofit work. The 550 x 980mm dimensions make it appropriate for standard roof window installations. Always verify compatibility with your specific VELUX window or Sun Tunnel model before ordering.
- Slate roof installations only
- Compatible with VELUX roof windows and Sun Tunnel systems
- New build and refurbishment applications
- Standard roof pitch installations in UK conditions
Installation and positioning
The flashing must be installed before the roof window or Sun Tunnel is fitted. The 8mm recessed design means the flashing sits below the surface of the slate tiles, creating a neat finish. Position the flashing centrally over the roof opening, ensuring it is level and square. The flashing should be secured according to VELUX installation instructions, with proper bedding in mortar or sealant to create a weather-tight seal. Slate tiles must be cut and fitted around the flashing perimeter to ensure complete coverage and water shedding.
- Install flashing before fitting the roof window or Sun Tunnel
- Position centrally and level over the roof opening
- Bed flashing securely in mortar or appropriate sealant
- Cut and fit slate tiles around the flashing perimeter
- Ensure all edges are sealed to prevent water ingress
Weather-tightness and maintenance
The recessed design and proper installation create a weather-tight seal that protects the building interior from water ingress. After installation, inspect the flashing regularly to ensure the mortar bed or sealant remains intact and that slate tiles are properly seated around the flashing edges. In areas prone to heavy rainfall or exposure, check the seal annually. Clean debris from around the flashing to prevent water pooling. Do not attempt to adjust or reposition the flashing once the roof covering is complete, as this may compromise the weather-tight seal.
- Inspect mortar bed and sealant annually for cracks or deterioration
- Clear debris from around the flashing perimeter
- Check that slate tiles remain properly seated
- Do not reposition flashing after roof covering is installed
Limitations and important notes
This flashing is designed exclusively for slate roofs and must not be used with other roof coverings such as tiles, asphalt shingles, or metal sheets. It is a coupled system and must be used with compatible VELUX roof windows or Sun Tunnels in the CK04 size range. The 8mm recess depth is specific to slate integration and cannot be adjusted. Installation must follow VELUX technical guidance to ensure warranty validity and long-term performance. This is a specialist product requiring careful handling on site to avoid damage to the recessed profile.
- Slate roofs only – not suitable for other roof coverings
- Must be used with compatible VELUX CK04 systems
- Recess depth is fixed at 8mm and cannot be altered
- Follow VELUX installation instructions for warranty compliance
- Handle carefully on site to protect the recessed profile