How and where to use guide
VELUX Twin and Combination Flashings 55x98cm EBW CK04 0021B
Typical applications and positioning
These flashings are designed for use at critical roof junctions in timber-framed buildings. Install them in roof valleys where two pitched roof planes meet, at hip joints where roof slopes converge at an angle, along ridge lines where roof planes meet at the peak, and at transitions between flat and pitched roof sections. The 55x98cm dimensions accommodate standard roof pitches and typical construction layouts. Proper positioning ensures water runs away from the junction and into the roof covering rather than pooling or penetrating the timber frame beneath.
- Roof valleys: where two pitched planes slope downward together
- Hip joints: where roof slopes meet at an external angle
- Ridge lines: where two roof planes meet at the peak
- Flat-to-pitched transitions: where flat roof sections meet pitched work
Installation and securing
Install the flashing before laying final roof coverings so that tiles, slates, or other materials overlap the flashing edges and direct water downward. Ensure the flashing sits firmly against the timber frame and roof structure with no gaps or voids beneath. Secure according to your roof covering type and local building practice, typically using appropriate fasteners that will not corrode or damage the plastic construction. The brown wood finish helps the flashing blend visually with standard roof coverings once installed.
- Position flashing before laying roof tiles or slates
- Ensure full contact with underlying timber structure
- Secure using appropriate fasteners for your roof type
- Allow roof covering to overlap flashing edges for water shedding
Durability and maintenance
The durable plastic construction resists weathering and UV exposure, providing long-term weather protection without the corrosion issues of metal flashings. Inspect flashings annually, particularly after severe weather, to ensure they remain properly seated and that roof coverings have not shifted. Clear any debris from valleys and roof junctions to prevent water pooling. The brown finish may fade slightly over time but does not affect the weather-tight performance of the flashing.
- Check annually for movement or gaps, especially after storms
- Clear leaves and debris from valleys and junctions
- Ensure roof coverings remain properly overlapped
- No painting or treatment required
Limitations and site considerations
These flashings are designed specifically for timber-framed buildings and pitched or flat roof combinations. Confirm the 55x98cm size suits your roof layout and junction dimensions before ordering. The plastic construction is durable but should not be exposed to extreme heat sources or direct flame. Install in dry conditions to ensure proper seating and adhesion. On exposed or high-altitude sites, pay particular attention to securing flashings against wind uplift.
- Confirm size suits your roof junctions and pitch
- Install in dry weather conditions
- Secure firmly on exposed or windy sites
- Not suitable for non-timber-framed buildings or specialist roof types