When installing a multiwall polycarbonate roof, one of the most important decisions is how to seal the open ends of the sheets. A common question is:

“Do I really need breather tape?”

Breather tape is a key component in ensuring the long-term clarity, cleanliness, and performance of multiwall polycarbonate sheets. This guide explains what it does, where it goes, and why it matters for any pergola, carport, lean-to, or garden-room roof.

What Is Breather Tape?

Breather tape is a specialist ventilated tape applied to the open bottom edge of multiwall polycarbonate sheets. It allows internal moisture to escape while helping block:

• Dust

• Dirt

• Insects

• Fine debris

It is always used together with solid aluminium tape, which seals the top edge of the sheet.

Browse breather and aluminium tapes:
👉 https://polycarbonatex.co.uk/collections/multiwall-accessories

Why Multiwall Polycarbonate Needs Breather Tape

Multiwall polycarbonate contains internal chambers (flutes). Over time, these flutes can collect:

• Natural moisture from condensation

• Dust carried by airflow

• Fine debris or insects

Without ventilation and protection, this may lead to:

• Internal condensation build-up

• Visible dirt or streaking inside the sheet

• Reduced light clarity

• Long-term staining inside the flutes

Breather tape helps manage moisture while keeping contaminants out.

Where Does Breather Tape Go?

Correct placement is essential:

1. Bottom Edge – Breather Tape

• Allows internal moisture to ventilate

• Prevents debris entering the flutes

• Supports long-term clarity

2. Top Edge – Solid Aluminium Tape

• Fully seals the sheet

• Helps prevent rainwater entering from above

3. End Closures Over Both Tapes

End closures protect the taped edges and provide a tidy finish.

Using the tapes and closures together creates a complete sealing system.

What Happens If You Skip Breather Tape?

Not using breather tape may lead to issues that are difficult to correct once the roof is installed:

• Condensation trapped inside the flutes

• Algae or dirt visible inside the sheet

• Persistent internal moisture

• Reduced internal clarity

These problems are usually permanent once contamination enters the flutes.

Is Breather Tape Needed on All Sheet Thicknesses?

Yes. Any multiwall polycarbonate sheet with open flutes should use:

• Breather tape on the bottom edge, and

• Solid aluminium tape on the top edge

This applies to:

• 4mm

• 6mm

• 10mm

• 16mm

• 25mm

Each sheet thickness benefits from correctly sealed ends.

How to Apply Breather Tape Correctly

For best results:

1. Ensure the sheet ends are clean, dry, and free from debris

2. Apply breather tape firmly to the bottom end

3. Apply solid aluminium tape to the top end

4. Fit end closures over both taped edges

5. Install sheets with a suitable roof pitch for natural drainage

Accessories for correct installation:
👉 https://polycarbonatex.co.uk/collections/multiwall-accessories

Breather Tape vs Aluminium Tape: What’s the Difference?

They work together, not interchangeably.

Does Ventilation Replace Breather Tape?

No. Even with good roof ventilation, moisture can still form inside the flutes. Breather tape specifically manages internal condensation, while ventilation manages airflow beneath the roof.

Both are beneficial, but they serve different functions.

Frequently Asked Questions

Is breather tape essential?

Yes — it helps prevent contaminants entering the flutes and supports moisture ventilation.

Can I use normal tape instead?

No. Standard tapes trap moisture and can lead to internal condensation.

Does breather tape stop leaks?

Breather tape is not a waterproofing product; it works as part of a complete end-sealing system.

Do I need breather tape at both ends?

No.

• Bottom edge: breather tape

• Top edge: aluminium tape