How and where to use guide
VELUX Twin and Combination Flashings 94x140cm EBW PK08 0021B
Suitable applications and roof types
This twin flashing is engineered for use with roof tiles, interlocking slate, thatch and profiled metal sheeting where the profile depth does not exceed 120mm. It is suitable for roof pitches ranging from 15° to 90°, covering most standard domestic pitched roofs through to near-vertical installations. The flashing creates a weather-tight seal at the critical interface between the window frame and roofing material, preventing water ingress at this vulnerable junction.
- Roof tiles and interlocking slate systems
- Thatch coverings
- Profiled metal sheeting up to 120mm profile depth
- Roof pitches from 15° to 90°
Installation and positioning
The flashing accommodates two roof windows positioned side by side with exactly 18mm spacing between the units. Measure and mark the window positions carefully before installation to ensure the correct gap is maintained. The flashing dimensions of 94x140cm are sized to cover the dual window installation footprint. Position the flashing so it sits properly under the upper roofing courses and over the lower courses, following the standard flashing installation sequence for your specific roof covering type.
- Maintain 18mm gap between the two window frames
- Install flashing under upper roof courses and over lower courses
- Ensure flashing sits flush with roofing material
- Check pitch angle is within 15° to 90° range before installation
Limitations and site considerations
This flashing is specifically designed for dual window installations with the specified 18mm spacing. Do not use for single window installations or where spacing differs significantly from this specification. The maximum roofing profile depth of 120mm must be observed; deeper profiles may compromise the weather-tight seal. On steep pitches approaching 90°, ensure adequate fixing and support during installation. In thatch applications, coordinate with your thatcher to ensure proper integration with the thatch layer.
- Not suitable for single window installations
- Roofing profile must not exceed 120mm depth
- Verify roof pitch is within specified range
- Thatch installations require coordination with thatcher
Maintenance and weather protection
After installation, inspect the flashing regularly to ensure the weather-tight seal remains intact, particularly after severe weather. Check that all edges are properly seated and that no gaps have developed between the flashing and roofing material. Keep the flashing clear of debris and moss growth which can trap moisture. If any water ingress is detected around the window frames, inspect the flashing seal immediately and reseat or replace if necessary. The flashing should provide long-term weather protection when correctly installed and maintained.
- Inspect seal regularly for gaps or movement
- Clear debris and moss from flashing edges
- Check for water ingress around window frames after heavy rain
- Reseat or replace flashing if weather-tight seal is compromised