What Do I Need for a Polycarbonate Roof? (Complete Kit Guide)
If you’re planning to build a pergola, lean-to roof, veranda or carport, one of the most common questions is:
👉 “What exactly do I need for a polycarbonate roof?”
It’s not just the sheets — a proper polycarbonate roofing system includes glazing bars, tapes, fixings and finishing trims. Missing even one component can lead to leaks, condensation or structural issues.
In this guide, we break down everything you need for a complete polycarbonate roofing kit, so you can plan your project with confidence.
Helpful resources mentioned throughout this guide:
Cut-to-size polycarbonate sheets
https://polycarbonatex.co.uk/products/cut-to-size-multiwall-polycarbonate-sheet
Multiwall accessories
https://polycarbonatex.co.uk/collections/multiwall-accessories
Glazing bar end caps
https://polycarbonatex.co.uk/collections/multiwall-accessories/products/corotherm-multiwall-polycarbonate-sheet-glazing-bar-end-cap
Delivery policy
https://polycarbonatex.co.uk/pages/delivery-policy
What Makes Up a Polycarbonate Roofing Kit?
A complete polycarbonate roof system consists of:
- Polycarbonate sheets
- Glazing bars
- Sealing tapes
- End closures
- Fixings
- Optional flashing
Each component plays a critical role in ensuring the roof is strong, watertight and long-lasting.
1. Polycarbonate Sheets
The sheets form the main surface of your roof.
They are available in different:
• Thicknesses (6mm, 10mm, 16mm, 25mm)
• Colours (clear, opal, bronze)
• Sizes
Choosing the Right Sheets
• 6mm → Small pergolas
• 10mm → Most pergolas & lean-tos
• 16mm → Larger roofs & better insulation
Cut-to-size sheets make installation much easier and more accurate.
Order here:
https://polycarbonatex.co.uk/products/cut-to-size-multiwall-polycarbonate-sheet
2. Glazing Bars
Glazing bars sit between sheets and secure them to the rafters.
They provide:
• Structural support
• Weatherproof sealing
• Proper spacing
Types of Glazing Bars
• Snap-fix (DIY-friendly)
• Screw-down (more secure for large roofs)
You will need:
👉 One glazing bar between each sheet
👉 Plus bars on the outer edges
3. Aluminium Sealing Tape (Top Edge)
Aluminium tape is applied to the top edge of each sheet.
It:
• Seals the sheet
• Prevents water ingress
• Protects internal chambers
4. Breather Tape (Bottom Edge)
Breather tape is applied to the bottom edge of each sheet.
It allows:
• Moisture to escape
• Airflow through the sheet
This prevents:
• Condensation build-up
• Internal mould or dirt
5. End Closures (U-Profiles)
End closures are fitted to the top and bottom of the sheet.
They:
• Protect sheet edges
• Improve water runoff
• Support sealing tapes
6. Fixings and Screws
Fixings secure the system to your structure.
These include:
• Screws
• Washers
• Fixing buttons
Correct fixings ensure:
• Stability
• Wind resistance
• Long-term durability
7. Glazing Bar End Caps
End caps seal the ends of glazing bars and prevent water entering.
Missing end caps are a common cause of leaks.
8. Optional: Wall Flashing (Lean-To Roofs)
If your roof is attached to a wall, you’ll need flashing.
Flashing:
• Seals the top edge
• Prevents water entering behind the roof
• Protects the wall connection
How to Calculate What You Need
To build a full kit, you need:
Step 1 — Measure roof width
Determines number of sheets
Step 2 — Measure roof projection
Determines sheet length
Step 3 — Check rafter spacing
Determines sheet width
Step 4 — Choose thickness and colour
Step 5 — Add accessories
What a Full Kit Looks Like (Example)
For a 3m x 2.5m lean-to roof:
You would typically need:
• 3 polycarbonate sheets
• 4 glazing bars
• Aluminium tape (top edges)
• Breather tape (bottom edges)
• End closures
• Fixings
• Flashing (if attached to wall)
Why Buying a Full Kit Is Better
Buying everything separately often leads to:
❌ Missing parts
❌ Incorrect quantities
❌ Compatibility issues
❌ Extra delivery costs
A full kit ensures:
✅ Everything fits together
✅ No missing components
✅ Faster installation
✅ Better performance
Using a Roof Calculator (Recommended)
The easiest way to get everything you need is to use a calculator.
A good calculator will:
• Calculate sheet sizes
• Select glazing bars
• Add correct accessories
• Provide total price
Accessories You Can Browse Separately
If you need individual components:
Browse here:
https://polycarbonatex.co.uk/collections/multiwall-accessories
Common Mistakes When Buying Materials
Avoid these:
❌ Forgetting breather tape
Leads to condensation
❌ Missing glazing bars
Sheets won’t install correctly
❌ No overhang or drip trim
Causes water issues
❌ Incorrect sheet sizes
Leads to poor fit and leaks
Cut-to-Size Sheets (Best Option)
Pre-cut sheets:
• Save time
• Reduce waste
• Ensure perfect fit
Order here:
https://polycarbonatex.co.uk/products/cut-to-size-multiwall-polycarbonate-sheet
Delivery Information
Check delivery details here:
https://polycarbonatex.co.uk/pages/delivery-policy
Conclusion
A polycarbonate roof is more than just sheets — it’s a complete system. Using the correct combination of sheets, glazing bars, tapes and fixings ensures your roof is strong, watertight and built to last.
By understanding exactly what you need and using a full kit or calculator, you can avoid common mistakes and complete your project with confidence.
