How and where to use guide
VELUX Twin and Combination Flashings 94x140cm EKL PK08 0021E
Typical applications and where to use
These flashings are designed for sealing roof penetrations in pitched timber-framed roofs. They create weathertight seals around chimneys, roof vents, soil pipes and skylights where water ingress poses a significant risk. The 94 x 140cm dimensions suit standard roof tile and slate applications. Confirm your roof pitch, penetration diameter and timber grade before ordering to ensure correct product selection.
- Chimneys and chimney stacks
- Roof ventilation pipes and ducts
- Skylight and roof window installations
- Soil and waste pipes penetrating the roof
- Pitched roofs with timber grades F16, F24 or F36
Installation and on-site guidance
Install flashings during roof construction or when replacing roof coverings. Position the flashing so the upper edge sits beneath the roof covering and the lower edge overlaps the covering below. Ensure the vinyl-coated polyester material is not creased or damaged during handling. Secure using appropriate fixings suitable for your roof covering type and timber grade. Bed the flashing in roofing cement or mastic where required by your roof design. Allow adequate overlap and ensure all edges are sealed to prevent water penetration at joints.
- Install before laying roof tiles or slates above the penetration
- Ensure upper edge is tucked under roof covering
- Use fixings appropriate to your timber grade and roof covering
- Seal all joints and edges with suitable roofing mastic
- Check that the flashing sits flush and does not create trip hazards
Durability and maintenance
The vinyl-coated polyester material is engineered to withstand prolonged weather exposure, high wind loads and temperature fluctuations. Inspect flashings annually, particularly after severe weather, to ensure the seal remains intact and no water is penetrating around the edges. Clear any debris, moss or lichen growth that may accumulate on the flashing surface. If damage occurs, repair or replace the affected section promptly to prevent water ingress into the roof structure.
- Inspect annually for signs of deterioration or separation
- Clear debris and organic growth to maintain water run-off
- Check mastic seals and reapply if cracked or shrunk
- Replace immediately if vinyl coating is torn or punctured
Important limitations and considerations
Always verify that your timber roof structure is graded F16, F24 or F36 before installation. Confirm the flashing dimensions suit your specific roof pitch and penetration size. These flashings are designed for pitched roofs only and are not suitable for flat roof applications. Do not use on roof structures with incompatible timber grades. Improper installation or use with unsuitable materials will compromise weatherproofing and may lead to water damage.
- Confirm timber grade compatibility before ordering
- Check product dimensions against your roof penetration size
- Not suitable for flat roofs or non-timber structures
- Unsuitable fixings or installation methods will void weather protection