How and where to use guide
VELUX Twin and Combination Flashings 55x98cm EKW CK04 S0312
Typical applications and suitability
This flashing is designed specifically for pitched roof installations where VELUX roof vents are being fitted. It works with standard VELUX units and is suitable for use with softwood timber grades F16, F24, and F32, which are commonly used in UK roof construction. The flashing accommodates the 55cm × 98cm aperture size, making it compatible with standard VELUX window dimensions. Multiple finish options are available to match different roof specifications and aesthetic requirements, allowing you to select the appropriate variant for your particular roofing material and colour scheme.
- Pitched roof installations only
- Compatible with timber grades F16, F24, and F32
- Fits standard VELUX roof vent units
- Available in multiple finishes for different roof types
Installation and positioning
The flashing must be positioned around the VELUX roof vent aperture to create a complete watertight seal. The 55cm × 98cm dimensions are designed to overlap the roof structure and the vent frame, directing water away from the opening and down the roof slope. Correct positioning is critical: the flashing should be installed so that the upper edge sits beneath the roof covering above the vent, whilst the lower edge extends over the roof covering below the vent. This overlapping arrangement ensures water runs over the flashing rather than behind it. The flashing must be securely fixed to the roof structure and vent frame according to VELUX installation guidance to prevent movement or lifting during high winds or roof movement.
- Position upper edge beneath roof covering above the vent
- Ensure lower edge overlaps roof covering below the vent
- Secure flashing to both roof structure and vent frame
- Check alignment before final fixing to ensure watertight seal
Weather resistance and durability
This flashing features durable construction specifically engineered to withstand weather exposure and the movement that occurs in pitched roofs as temperatures and humidity fluctuate. The materials and finish options are selected to resist corrosion, UV degradation, and water penetration over the long term. However, the flashing's effectiveness depends entirely on correct installation and maintenance. Any gaps, misalignment, or loose fixings will compromise the watertight seal and allow water ingress.
- Inspect flashing annually for signs of movement or damage
- Check that all fixings remain tight and secure
- Clear debris from around the flashing to prevent water pooling
- Address any gaps or separation immediately to prevent leaks
On-site handling and installation tips
Handle the flashing carefully during transport and storage to avoid denting or bending, which could compromise the seal. Before installation, verify that your VELUX unit dimensions match the 55cm × 98cm specification and that your timber grades are F16, F24, or F32. Confirm that the finish option you have selected is appropriate for your roofing material and colour. During installation, work methodically to ensure the flashing sits evenly and makes full contact with both the roof structure and vent frame. Use appropriate fixings for your roof type and ensure they are installed at the correct spacing to prevent water ingress. Do not attempt to force the flashing into position if it does not fit properly, as this may damage the seal or the vent frame.
- Verify VELUX unit size matches 55cm × 98cm specification
- Confirm timber grade compatibility before installation
- Check finish option matches your roofing material
- Use appropriate fixings and spacing for your roof type
- Ensure full contact between flashing and roof structure