Fixing and buying guide

What this product is and who it is for

This is a tile flashing assembly with integrated insulation, not a roof window itself. It is the installation component that sits between your VELUX roof window frame and the surrounding roof tiles, creating a watertight seal and maintaining thermal continuity. It is for builders, roofers, and serious DIY installers undertaking new roof window installations or replacing existing flashings during refurbishment work. You will need a compatible VELUX Pro+ roof window to use this flashing.

Compatibility and sizing

This flashing is sized 780 × 1800mm (78 × 180cm) and is designed for VELUX Pro+ roof windows and Sun Tunnel systems. Before ordering, confirm that your roof window model is compatible with the MK12 2000 flashing code. Check your window documentation or contact VELUX technical support if you are unsure. The flashing dimensions relate to the opening size required in your roof structure, not the finished window size.

• Compatible with VELUX Pro+ roof window range
• Also compatible with VELUX Sun Tunnel systems
• Fixed dimensions: 780 × 1800mm — measure your roof opening carefully
• Do not use with non-VELUX windows or incompatible VELUX models

Insulation and thermal performance

The integrated 120mm insulation layer supports the thermal efficiency of your installation and helps prevent thermal bridging at the roof junction. This thickness is engineered to work with the flashing profile and the window frame to maintain consistent U-values and reduce heat loss. The insulation also helps create a visually consistent roof line by supporting the tile profile around the window perimeter.

Pre-installation checks and preparation

Before fitting, inspect the flashing for any damage in transit. Ensure your roof structure is prepared to the correct opening dimensions (780 × 1800mm) and that the surrounding roof deck is sound and level. Check that your VELUX window frame is to hand and that you have all necessary sealing and fixing materials. Confirm roof tile type and pitch compatibility with VELUX guidance — this flashing is designed for standard pitched tile roofs typical in UK construction. Have a helper available, as this is a two-person installation task.

• Verify roof opening is exactly 780 × 1800mm
• Check roof deck is level, sound, and free from debris
• Confirm VELUX window frame is compatible and ready to install
• Gather all sealing, flashing tape, and fixings before starting
• Ensure roof conditions are dry and suitable for working at height