Fixing and buying guide

What this product is and who it is for

This is a complete recessed flashing system for VELUX roof windows measuring 780×980mm (78×98cm). It is intended for builders, roofers, and serious DIY installers who are fitting a compatible VELUX roof window or Sun Tunnel system and need a weather-tight, visually integrated flashing solution. The recessed design sits neatly within the roof line rather than standing proud, giving a professional finish. It works for both new build projects and refurbishment of existing roofs.

Compatibility and sizing

This flashing kit is sized specifically for 780×980mm roof window openings. Before ordering, confirm that your VELUX window or Sun Tunnel system is the 78×98cm (MK04) size. The 90mm tile flashing depth is engineered to work with standard UK roof tile profiles. Check your roof pitch and tile type with the VELUX specification or installation manual to ensure this system is suitable for your application.

• Designed for 78×98cm (780×980mm) openings only
• 90mm tile flashing depth for standard UK tile profiles
• Compatible with VELUX roof windows and Sun Tunnel systems in this size
• Verify roof pitch and tile type against VELUX documentation before purchase

What is included in the pack

The kit contains two main components: a recessed tile flashing and the BDX 2000F installation kit. The tile flashing provides the weather-tight interface between the window frame and roof tiles. The BDX 2000F components handle the mechanical fixing and sealing of the window to the flashing. Together, these ensure a complete, integrated installation without the need to source additional flashing parts.

• Recessed tile flashing (90mm depth)
• BDX 2000F installation components
• All components sized for 78×98cm openings

Pre-installation checks and preparation

Before fitting, inspect the roof opening to confirm it measures 780×980mm and that the surrounding roof structure is sound and level. Check that your VELUX window frame is the correct size and that you have the matching installation manual. Ensure roof tiles are in good condition around the opening area, as the flashing will integrate with them. Have the BDX 2000F components and tile flashing laid out and checked against the kit contents. If you are working on a refurbishment, remove any old flashing carefully and make good the roof structure before installing this system.

• Measure the roof opening to confirm it is 780×980mm
• Verify the VELUX window frame size matches this kit
• Check roof tiles and structure are sound and level
• Have the VELUX installation manual to hand
• For refurbishment work, remove old flashing and make good the roof first