Fixing and buying guide

What this product is and who needs it

Twin and combination flashings are metal seals that fit around roof penetrations to prevent water leaking into the building. They are specifically engineered for timber frame roofs and work alongside roof windows or similar installations. If you are installing a VELUX window or need to weatherproof an opening in a pitched roof, this flashing provides the essential barrier against rain and moisture ingress.

Compatibility and sizing

This flashing is graded EBW and sized at 78x98cm, which accommodates standard roof configurations. It is designed for pitched roofs with a maximum height of 4m and is intended for use in timber frame construction. Check your roof window or penetration dimensions against the 78x98cm size before ordering to ensure proper fit. The extruded aluminium construction is compatible with standard roofing materials and timber frame structures.

What is included and pre-installation checks

You receive one flashing unit measuring 78x98cm. Before installation, inspect the flashing for any damage during transport. Verify that your roof opening matches the flashing dimensions and that your timber frame is sound and properly prepared. Ensure the roof pitch is suitable for this product and that the installation height does not exceed 4m. Have all necessary fixings and sealants ready before beginning work.

• Check flashing dimensions match your roof opening
• Inspect for transport damage before fitting
• Confirm roof pitch is appropriate for pitched roof use
• Verify timber frame is in good condition
• Gather fixings and weatherproofing sealant in advance

Installation and performance

The extruded aluminium construction provides durability and weather resistance in demanding conditions. The flashing must be properly sealed and fixed to prevent water ingress around the roof penetration. Follow VELUX installation guidance for your specific roof window or application. The robust finish is designed to withstand exposure to rain, wind, and temperature variation typical of UK pitched roofs.

• Extruded aluminium resists corrosion and weathering
• Suitable for roofs up to 4m high
• Durable finish handles harsh environmental exposure
• Must be sealed and fixed according to manufacturer instructions