Flashing tape is a flexible, self-adhesive, bitumen-based tape designed to create a waterproof, airtight seal on roofs, walls and building joints. It’s an easy alternative to traditional lead flashing and is ideal for DIY and trade repairs.

What you’ll need

Flashing tape, broom or brush, scraper, clean cloth, roller or firm pressure tool, bituminous primer (for porous surfaces), scissors or knife.

1. Preparation

• Ensure the surface is sound, clean and dry.
• Remove dust, dirt, grease and loose material.
• Fill any deep cracks or holes wider than 3mm before applying tape.
• For porous surfaces such as brick, concrete or masonry, apply a bituminous primer and allow it to dry.

2. Application

• Cut the tape to the required length.
• Peel away the backing and press the tape firmly into place.
• Apply from the bottom upwards so overlaps shed water naturally.
• Overlap joints by at least 25–50mm to maintain a continuous seal.
• Use a roller or firm pressure along the full length, edges and corners to remove air bubbles and ensure full adhesion.

3. Finishing

• Check all edges are fully bonded.
• Apply additional pressure if required, especially around joints and corners.
• The seal is waterproof immediately once applied.

Key tips

• Do not apply below 5°C; warm the tape before use in cold conditions.
• Use gentle heat on cold surfaces to improve adhesion if needed.
• Always roll the tape thoroughly – loose edges are the most common cause of leaks.
• Ideal for sealing roof joints, chimney stacks, parapets, rooflights, gutters, pipes and wall penetrations.