How and where to use guide
VELUX Twin and Combination Flashings 55x118cm EKL CK06 S0122
Suitable applications and roof types
This flashing kit is intended for new installations or replacements of two VELUX roof windows in vertical alignment on natural slate roofs. It is not suitable for other roof coverings such as clay tiles, concrete tiles, or sheet materials. The kit works across a wide range of roof pitches from shallow 15° pitches through to near-vertical 90° installations, making it adaptable to most residential and commercial roof angles. Ensure your slate tiles are natural slate and do not exceed 8mm in thickness; thicker or artificial slate may not integrate properly with the flashing profile.
- Natural slate roofs only – up to 8mm thickness
- Two windows in vertical alignment with 100mm frame gap
- Roof pitches 15° to 90°
- Not suitable for clay, concrete, or sheet roof coverings
Installation and positioning
Position the two roof windows vertically one above the other with exactly 100mm clearance between the bottom of the upper window frame and the top of the lower window frame. This spacing is critical for the flashing kit to function correctly and maintain weathertightness. Install the lower window first, then fit the flashing components around it before positioning the upper window. Ensure the roof pitch is measured accurately before installation; the flashing is engineered for the stated pitch range and will not seal properly if installed on pitches outside this range. The kit dimensions of 55 × 118cm are designed to accommodate this standard dual-window configuration.
- Install lower window first, then upper window
- Maintain exactly 100mm gap between window frames
- Verify roof pitch is between 15° and 90°
- Fit flashing components in sequence as per VELUX installation instructions
Weatherproofing and sealing
The flashing kit includes all components necessary to create a weathertight seal between the windows and the slate roof. The design integrates with natural slate tile profiles to prevent water ingress at the critical junction points. Ensure all components are correctly seated and that slate tiles are properly aligned around the flashing. Pay particular attention to the areas where the upper and lower flashings meet, as this is where water can penetrate if not sealed correctly. Do not attempt to modify or cut the flashing components; they are precision-engineered for this specific window configuration and roof type.
- All sealing components included in the kit
- Integrates with natural slate tile profiles
- Do not modify or cut flashing components
- Check alignment of slate tiles around flashing after installation
Maintenance and on-site considerations
After installation, inspect the flashing annually, particularly after severe weather, to ensure slate tiles remain properly aligned and no debris has accumulated in the valleys around the windows. Clear any moss, lichen, or leaf debris that may collect around the flashing edges. Do not pressure-wash the area as this can dislodge slate tiles or force water under the flashing. If slate tiles become loose or damaged, repair or replace them promptly to maintain the weathertight seal. Store the kit in a dry location before installation and handle all components carefully to avoid damage during transport to site.
- Inspect annually for loose slate or debris accumulation
- Clear moss and leaves from flashing valleys
- Do not pressure-wash the installation area
- Replace damaged slate tiles immediately to maintain weatherproofing