How and where to use guide
VELUX Twin and Combination Flashings 66x118cm EBW FK06 0021B
Installation and positioning
Install the flashing around the VELUX rooflight opening before laying roof tiles or slates. The flashing must be positioned so that the lower edge overlaps the roof covering below the window by a minimum of 30mm. This overhang is essential for optimal performance and ensures water runs off the flashing rather than pooling behind it. The flashing should be secured firmly to the timber roof structure to prevent movement during installation and after exposure to weather. Ensure the flashing sits flush against the rooflight frame to maintain the weather-tight seal.
- Position flashing with 30mm minimum overhang below the rooflight
- Secure firmly to timber roof structure before laying roof covering
- Ensure full contact between flashing and rooflight frame
- Check that flashing sits level and does not rock or shift
Suitability and limitations
These flashings are designed specifically for use with VELUX rooflights on pitched roofs up to 3 metres high. They are suitable only for timber roof structures graded F18 and above, which indicates adequate structural strength for the installation. The durable plastic material resists weathering and UV exposure, but the flashing is not intended for use on flat roofs, roof heights exceeding 3 metres, or with substandard timber grades. Always verify your roof structure meets the minimum F18 timber grade requirement before installation.
- Suitable for pitched roofs only, maximum height 3 metres
- Requires timber grade F18 or above
- Not suitable for flat roofs or low-pitched applications
- Durable plastic resists harsh weather but check for damage before use
On-site handling and maintenance
Store the flashing in a dry location on site before installation to prevent dirt accumulation in the seal areas. Handle carefully to avoid cracking or distorting the plastic, particularly in cold weather when the material may be less flexible. After installation, inspect the flashing periodically to ensure the seal remains intact and that no debris has accumulated along the edges. Clear any moss, leaves, or dirt that may collect on the flashing surface, as this can trap moisture and compromise the weather-tight seal over time.
- Store dry and protected from site debris before installation
- Handle carefully to avoid cracking or distortion
- Inspect periodically for damage or seal deterioration
- Clear debris and moss from flashing surface to maintain water drainage