How and where to use guide

Suitable applications and roof types

This twin flashing is intended for dual roof window installations on pitched tile roofs. It works with standard clay, concrete, or slate tiles up to 120mm in profile depth. The flashing is not suitable for roofs with tile profiles exceeding 120mm, flat roofs, or metal sheet roofing. It is designed to work exclusively with compatible VELUX roof window ranges and should only be used where two windows are positioned with a 100mm gap between them. If your roof has a steeper pitch, deeper tile profile, or requires a different window spacing, you will need an alternative flashing configuration.

• Pitched tile roofs only, with tile profiles up to 120mm maximum
• Dual window installations with 100mm spacing between units
• Compatible with standard VELUX roof window ranges
• Not suitable for profiles exceeding 120mm or non-tile roof types

Installation and on-site guidance

The prefabricated design allows straightforward installation without custom metalwork. Before fitting, ensure both roof windows are correctly positioned with the 100mm gap maintained between them. The flashing must be installed in sequence: first secure the flashing to the roof structure, then integrate it with the window frames, and finally seal all joints to create a weathertight barrier. Correct installation is essential to prevent water ingress. Work should be carried out in dry conditions, and all fixings must be secure before the roof is re-tiled. If the gap between windows differs from 100mm or tile profiles exceed 120mm, do not force the flashing as this will compromise the weathertight seal.

• Install only in dry weather conditions
• Verify both windows are positioned with exactly 100mm gap before fitting flashing
• Secure flashing to roof structure first, then integrate with window frames
• Ensure all joints are sealed to prevent water penetration
• Do not use if tile profile exceeds 120mm or window spacing differs from 100mm

Maintenance and durability

Once installed, the flashing requires minimal maintenance if fitted correctly. Periodically inspect the seal around both windows, particularly after severe weather, to ensure no water ingress has occurred. Clear any debris such as moss or leaves from the flashing surface to maintain drainage. The prefabricated construction means there are no on-site joints to maintain, reducing potential weak points. If water staining or damp appears around either window frame, the flashing seal may have been compromised and professional inspection is recommended.