Fixing and buying guide

What this product is and who needs it

Twin and combination flashings are essential components that seal the gap between a roof window or penetration and the surrounding roof tiles or slates. They prevent water ingress at vulnerable points where the roof structure is interrupted. These flashings are for builders, roofers, and serious DIY installers working on pitched roof projects where VELUX windows or similar penetrations need weatherproofing. The combination design offers flexibility across different roof pitches and building layouts.

Size, compatibility and pack contents

This flashing measures 55x78cm (21.6 x 30.7 inches) and is designed for standard roofing configurations. It is compatible with VELUX roof windows and similar roof penetrations. The product is supplied as a twin and combination flashing unit. Confirm your roof window size and pitch angle before ordering to ensure correct fit. If your installation requires a different size or configuration, check the full VELUX flashing range.

• Size: 55x78cm suits most standard roof window installations
• Twin and combination design provides installation flexibility
• Compatible with VELUX roof windows and equivalent penetrations
• Verify your specific roof window model and pitch before purchase

Material and durability

The flashing is constructed from FSC-certified timber with a coated steel finish. This combination provides structural integrity and weather resistance. The coated steel component protects against corrosion and wind-driven rain, whilst the FSC timber meets sustainable forestry standards. This specification ensures long-term performance on exposed pitched roofs.

• FSC-certified timber construction
• Coated steel finish resists corrosion and weather exposure
• Engineered to withstand wind-driven rain and snow loads
• Suitable for pitched roof applications

Pre-installation checks and preparation

Before fixing, inspect the flashing for any damage to the timber or steel coating. Ensure your roof structure is sound and the opening dimensions match the 55x78cm specification. Check that surrounding roof tiles or slates are in good condition and can be lifted or removed to allow proper flashing installation. Have appropriate roofing sealant, lead or zinc soakers, and fixing materials ready. Confirm the roof pitch is within the design range for this flashing type.

• Inspect timber and coated steel finish for transport damage
• Verify opening size matches the 55x78cm flashing dimensions
• Check roof tiles or slates are sound and can be lifted safely
• Gather roofing sealant and compatible fixing materials before starting
• Confirm roof pitch is suitable for this flashing design