Fixing and buying guide

What this product is and who needs it

This is a standard rooflight flashing—a rubber seal that sits between your rooflight frame and the roof structure to prevent water leaking into the building. You need it whenever you install or replace a rooflight in a pitched roof. It suits both domestic loft conversions and commercial roof projects where weather protection is critical.

Compatibility and sizing

The 78×140cm profile is designed for standard rooflight openings and fits into confined roof spaces without excessive bulk. It is compatible with VELUX rooflights and other rooflight brands, so you can use it in mixed-specification projects. The flashing is engineered for timber grades F16 and F24, which covers the vast majority of domestic and commercial roof timbers.

• Width: 78cm, Length: 140cm
• Material: 4mm black EPDM rubber
• Suitable for timber grades F16 and F24
• Works with VELUX and other rooflight brands

Pre-installation checks

Before fitting, confirm that your rooflight opening matches the 78×140cm profile and that your roof timbers are graded F16 or F24. Check that the rooflight frame is square and level, and that the opening edges are clean and free from debris, splinters, or protruding nails. Ensure the roof deck is dry and ready to receive the flashing. If you are replacing an old flashing, remove all old sealant and rubber completely.

• Verify rooflight opening dimensions against the 78×140cm flashing size
• Confirm timber grades F16 or F24
• Check rooflight frame is square and level
• Clean opening edges and ensure roof deck is dry

Why EPDM rubber and what to expect

EPDM (ethylene propylene diene monomer) rubber is the industry standard for rooflight flashings because it resists UV exposure, remains flexible in temperature changes, and provides a reliable long-term watertight seal. The 4mm thickness balances durability with minimal bulk, so it sits neatly between the rooflight frame and roof structure without creating installation difficulties. Black colour helps it blend with most roof coverings.