How and where to use guide
VELUX Twin and Combination Flashings 55x118cm EKW CK06 0021E
Typical applications and installation locations
These combination flashings are used when two VELUX roof windows need to be installed in the same roof slope with controlled spacing. Common applications include creating dual light sources in loft conversions, master bedrooms, or open-plan spaces where a single window would be insufficient. The 100mm frame spacing is critical—measure carefully between the outer edges of adjacent window frames to confirm compatibility. Installation is suitable for profiled roofing materials such as concrete or clay tiles, fibre cement sheets, and metal profiled decking, provided the profile depth does not exceed 120mm. Do not use on flat roofs or where roof pitch exceeds the manufacturer's specifications.
- Loft conversions and bedroom extensions requiring dual natural light
- Open-plan living areas where two windows improve daylighting
- Profiled tile or sheet roofing with profile depth up to 120mm
- Roof pitches suitable for standard VELUX window installation
Installation steps and site preparation
Begin by confirming the exact 100mm spacing between the two window frames—this is essential for the flashing to seal correctly. Cut the roof opening to accommodate both windows and the combination flashing as a single unit. Position the flashing so it sits flush against the roof surface, with the upper edge tucked under the roofing material above and the lower edge overlapping the roofing below. Secure the flashing according to VELUX instructions, ensuring all fixing points are sealed. The flashing must be installed before the windows themselves are fitted. Work methodically to avoid gaps or misalignment, as the watertight performance depends on correct positioning. On site, protect the flashing from foot traffic and debris during subsequent trades' work.
- Measure 100mm spacing between window frame edges before cutting roof opening
- Install flashing as a complete unit before fitting individual windows
- Position upper edge under existing roofing material, lower edge over material below
- Secure all fixing points and seal according to VELUX guidance
- Protect flashing from damage during remaining roof works
Maintenance and performance
The maintenance-free exterior finish means no regular treatment, painting, or sealing is required. Inspect the flashing annually during routine roof maintenance to ensure no debris has accumulated in valleys or around the window frames, as blockages can impede water drainage. Clear any moss, leaves, or dirt using a soft brush—avoid pressure washing or abrasive methods that could damage the finish. Check that the seal between the flashing and roof material remains intact; if cracks or gaps appear after several years, contact a qualified roofer for remedial work. The flashing is designed for long-term durability without intervention, but proper installation and freedom from obstruction are essential to maintain watertight performance.
- No painting, staining, or protective treatments required
- Clear debris and moss annually using soft brush only
- Avoid pressure washing or abrasive cleaning methods
- Inspect seals and joints annually for signs of deterioration
- Contact a qualified roofer if cracks or gaps develop
Limitations and important considerations
This flashing is designed exclusively for 100mm frame spacing—do not attempt to use it where windows are closer or further apart, as the seal will be compromised. It is not suitable for roofing materials with profile depth exceeding 120mm, flat roofs, or roof pitches outside the standard VELUX installation range. The combination flashing is a single integrated unit; it cannot be modified or cut to fit non-standard configurations. Ensure the roof structure and opening are prepared to exact specifications before installation begins. If your roof has unusual profile depths, spacing requirements, or pitch considerations, consult VELUX technical support or a qualified roofer before ordering.
- Only for 100mm frame spacing—not adjustable for other distances
- Profiled roofing depth must not exceed 120mm
- Not suitable for flat roofs or non-standard roof pitches
- Cannot be cut or modified to fit custom configurations
- Verify roof specifications before purchase and installation