How and where to use guide
VELUX Twin and Combination Flashings 55x118cm EKW CK06 S0312
Typical applications
These combination flashings are designed for pitched roof work where two roof planes meet at different angles or where multiple roof configurations intersect. Common applications include sealing junctions between main roof and dormer windows, valleys where roof slopes converge, roof extensions, and complex roof geometries. The 55×118cm size is suited to standard domestic and commercial pitched roof installations. Use these flashings in both new construction and repair work where existing flashing has failed or where roof modifications require new junction protection.
- Dormer window installations and roof-to-wall junctions
- Valley flashings where two pitched roof slopes meet
- Roof extensions and additions to existing pitched roofs
- Repairs to failed or damaged combination flashings
- Complex roof angles requiring dual flashing coverage
Installation and positioning
Position the flashing at the junction point before securing to the roof structure. The flashing must overlap existing roof covering and be integrated with the roof membrane or tiles to create a continuous watertight seal. Ensure the flashing is correctly oriented to direct water downslope and away from the junction. Secure according to roof type and local building regulations. The flashing should be installed before final roof covering is applied in new work, or carefully lifted and repositioned in repair situations. Proper overlap and sealing at all edges is critical to prevent wind-driven rain penetration.
- Install at roof junctions before final covering is applied
- Ensure downslope orientation to shed water effectively
- Overlap existing roof covering by minimum required distance
- Seal all edges and joints to prevent water ingress
- Secure firmly to prevent wind uplift and movement
Weather resistance and limitations
These flashings are engineered to withstand wind-driven rain and snow loads typical of UK pitched roof exposure. They provide reliable protection in harsh weather conditions when correctly installed. However, effectiveness depends on proper installation, correct overlap, and complete sealing of all joints and edges. The flashing alone cannot compensate for poor roof pitch, inadequate slope, or damaged surrounding roof covering. Regular inspection is recommended, particularly after severe weather events, to ensure seals remain intact and no water ingress has occurred.
- Rated for wind-driven rain and snow protection on pitched roofs
- Effectiveness depends on correct installation and complete sealing
- Not suitable for flat or low-pitch roofs without additional measures
- Inspect regularly for seal integrity and water ingress signs
- Replace if damaged, cracked, or seals have deteriorated
On-site handling and maintenance
Handle flashings carefully during transport and storage to avoid bending or creasing that could compromise the watertight seal. Store flat and protected from weather before installation. Once installed, inspect annually and after severe weather to ensure seals remain effective and no debris has accumulated at the junction. Clear any moss, leaves, or debris that could trap moisture. Check that the flashing has not lifted or shifted due to wind or thermal movement. If seals show signs of cracking, separation, or deterioration, plan replacement to prevent water ingress and subsequent roof damage.
- Transport and store flat to prevent damage to sealing surfaces
- Protect from weather and site debris before installation
- Inspect annually for seal integrity and water ingress
- Clear debris and moss from junction areas
- Monitor for movement, lifting, or seal deterioration