Advice – Choosing the Right Flashing Tape for Polycarbonate

When working with polycarbonate roofing sheets, choosing the correct flashing tape is essential for a secure, watertight seal and for protecting your panels from long-term damage.

Why Bitumen-Based Flashing Tape is Unsuitable for Polycarbonate

Although many flashing tapes are made with a bitumen adhesive, these should not be used with polycarbonate. Bitumen is chemically incompatible with polycarbonate and can cause:

• Material damage – Bitumen can attack the surface of the sheet, leading to discolouration, brittleness, and long-term weakening.
• Adhesive breakdown – The chemical reaction reduces adhesion over time, increasing the risk of leaks and water ingress.
• Shortened lifespan – Using the wrong tape can drastically reduce the durability and appearance of your polycarbonate installation.
• The Right Choice – Butyl-Based Flashing Tape

For polycarbonate, we always recommend a butyl-based flashing tape. Unlike bitumen, butyl rubber adhesives are chemically compatible with polycarbonate and create a strong, long-lasting bond without risk of damage.

When selecting flashing tape, check for:

• Butyl-based adhesive – safe for use with polycarbonate.
• Non-bituminous formulation – avoids harmful chemical reactions.
• Clear manufacturer guidance – look for tapes that specifically state they are suitable for polycarbonate.
• Correct installation – even the best tape requires clean, dry surfaces and careful application to perform effectively.

How to Apply Flashing Tape

Installing butyl flashing tape correctly will ensure the best results.

1. Prepare the Surface
2. Clean thoroughly to remove dust, dirt, or moisture.
3. For rough or porous surfaces, a suitable primer may help improve adhesion.
4. Measure and Cut
5. Measure the area carefully.
6. Cut the tape to length using a sharp knife or scissors, allowing extra length for overlaps.
7. Apply the Tape
8. Peel away the backing slowly.
9. Apply the tape to the surface, starting from the centre and pressing outwards to remove air bubbles.
10. Use a hand roller for firm, even pressure.
11. Seal the Edges
12. Overlap strips by several inches to create a continuous waterproof seal.
13. Press down firmly on all edges and joins.

Where to Use Flashing Tape

Flashing tape is ideal for creating a watertight seal where:

• Polycarbonate panels meet a brick wall.
• Two polycarbonate panels join together.
• Extra protection is needed against water ingress around edges and seams.

Our Self-Adhesive Flashing Tape features a durable aluminium foil surface with a strong adhesive backing. With a lead-look finish, it provides a neat, professional appearance while serving as an effective alternative to traditional lead flashing.

• Available in 10m rolls, with widths of 150mm or 225mm.
• Suitable for multiwall or twinwall polycarbonate sheets.
• Quick and simple to install – just press into place for an instant seal.

Important Notes:

• Images are for illustration purposes; colour and size may vary.
• Depending on supplier stock, material and product branding may vary.
• Always ensure you are using the correct tape type for polycarbonate.

By choosing a butyl-based flashing tape and following correct installation, you can protect your polycarbonate roof or canopy from leaks, extend its lifespan, and achieve a clean, professional finish.