Can You Screw Into Polycarbonate Sheets? (Quick Answer)
👉 You should NOT screw directly through multiwall polycarbonate sheets in most roofing systems.
Instead, sheets should be installed using:
• Glazing bars
• Fixing buttons (if required)
Why You Should NOT Screw Directly Into Sheets
1. Expansion and Contraction
Polycarbonate expands and contracts with temperature.
If you screw directly through the sheet:
• Movement is restricted
• Stress builds up
• Cracks can form
2. Risk of Cracking
Direct screws create pressure points.
This can lead to:
• Cracks around the hole
• Structural weakness
• Long-term failure
3. Leaks
Screwing through sheets can create:
• Small gaps
• Entry points for water
Even with washers, leaks can occur over time.
4. Reduced Lifespan
Incorrect fixing reduces the durability of the sheet.
Correct Way to Fix Polycarbonate Sheets
1. Use Glazing Bars (Recommended Method)
Glazing bars are designed to:
• Hold sheets securely
• Allow expansion
• Create a watertight seal
They are the standard method for:
• Pergolas
• Lean-to roofs
• Verandas
Browse here:
https://polycarbonatex.co.uk/collections/multiwall-accessories
2. Use Fixing Buttons (Alternative Method)
Fixing buttons are sometimes used when:
• Glazing bars are not used
• Sheets are fixed directly to rafters
How They Work
• A screw passes through a button
• Pressure is spread evenly
• Movement is still allowed
Important
Even with buttons:
👉 Do NOT overtighten
When Can You Screw Into Polycarbonate Sheets?
There are limited situations where it may be acceptable:
Corrugated Sheets (PVC or Solid Polycarbonate)
These are designed to be:
• Screwed through peaks
• Installed with washers
Small DIY Structures
In some simple builds, fixing buttons may be used.
Important
For multiwall polycarbonate roofing systems, glazing bars are always the better option.
What Happens If You Screw Directly Into Sheets?
Common problems include:
❌ Cracking around screws
Due to expansion pressure
❌ Water leaks
From poor sealing
❌ Bowing or warping
From restricted movement
❌ Noise in wind or heat
From stress release
How to Fix Incorrectly Screwed Sheets
Option 1 — Remove Screws and Reinstall Properly
• Remove direct fixings
• Install glazing bars
• Replace damaged sheets if needed
Option 2 — Use Fixing Buttons
If removing screws isn’t possible:
• Replace with proper buttons
• Ensure correct spacing
Option 3 — Replace Damaged Sheets
If cracking has occurred:
Order replacements here:
https://polycarbonatex.co.uk/products/cut-to-size-multiwall-polycarbonate-sheet
Best Practice for Fixing Polycarbonate Sheets
✅ Use glazing bars wherever possible
Most reliable method
✅ Allow expansion
Do not restrict movement
✅ Use correct accessories
Ensures proper installation
✅ Avoid overtightening
Prevents stress damage
✅ Use correct sheet size
Improves fit and stability
Accessories You’ll Need
A proper system includes:
• Glazing bars
• Fixings
• Sealing tapes
• End closures
Browse here:
https://polycarbonatex.co.uk/collections/multiwall-accessories
Cut-to-Size Sheets for Better Installation
Using correctly sized sheets reduces:
• Need for adjustments
• Risk of incorrect fixing
• Installation errors
Order here:
https://polycarbonatex.co.uk/products/cut-to-size-multiwall-polycarbonate-sheet
Delivery Information
Check delivery here:
https://polycarbonatex.co.uk/pages/delivery-policy
Conclusion
While it may seem easier to screw directly into polycarbonate sheets, it is not recommended for most roofing systems. Doing so can lead to cracking, leaks and reduced lifespan.
The best approach is to use glazing bars or fixing buttons, allowing the sheets to expand and contract naturally. With the correct installation method, your polycarbonate roof will be strong, watertight and built to last.
