Fixing and buying guide

What this product is and who it is for

This is a complete flashing system for integrating VELUX roof windows or Sun Tunnel systems into pitched roofs covered with plain tiles. The kit is intended for builders, roofers, and experienced DIY installers working on both new build and refurbishment projects. It delivers a weather-tight seal and maintains visual consistency with the existing roof finish, which is critical for long-term roof integrity in UK weather conditions.

Compatibility and sizing

This flashing kit is compatible with VELUX roof window and Sun Tunnel systems and is designed specifically for plain tile roofs with a maximum tile thickness of 14mm. The 1140×1180mm dimensions are sized to accommodate standard roof window openings. Before purchase, confirm that your roof tile type is plain tile (not interlocking or slate) and measure the tile thickness to ensure it does not exceed 14mm. Verify the roof window model you intend to install is compatible with VELUX standard flashing systems.

• Suitable for plain tile roofs only, up to 14mm thickness
• Dimensions 1140×1180mm for standard roof window openings
• Compatible with VELUX roof windows and Sun Tunnel systems
• Not suitable for interlocking tiles, slate, or thicker tile profiles

What is included

The kit contains a complete flashing assembly plus BDX and BFX installation products. These components work together to create the weather-tight seal around the roof window opening and integrate the flashing with the tile roof structure. All components needed for a standard installation are supplied in this single kit.

• Standard flashing assembly
• BDX installation product
• BFX installation product

Pre-installation checks

Before fixing, inspect your roof structure to confirm plain tile coverage, verify tile thickness is 14mm or less, and check that the roof opening dimensions align with the 1140×1180mm flashing size. Ensure the VELUX roof window or Sun Tunnel system you are installing is compatible with standard flashing. Clear the roof opening of debris and loose tiles, and confirm adequate roof ventilation and structural support around the opening. Have all necessary tools and safety equipment ready, including roof access equipment and weather protection for the open roof during installation.