How to Install Polycarbonate Sheet Fixings

How to Install Polycarbonate Sheet Fixings?

When installing polycarbonate sheets that are wider than normal they are more prone to wind uplift and sheet sag. A solution to help prevent wind uplift and sheet sag is to add cross purlins and use polycarbonate sheet fixings to secure the sheets at their centres.

In addition, with an increase in extreme weather the use of fixing buttons can help to strength your roof against snow loading and other weather!

Do you need to install Polycarbonate sheet fixings, like our Alukap-XR Fixing Buttons, on every roof construction? No - it’s a myth! You should only use polycarbonate roofing sheet fixings when your sheets have purlins supporting them due to be wider than normal, approximately one metre plus. For the majority of applications, we suggest keeping sheets widths and rafter distances at a sensible width and use glazing bars, like our Snapa PVC Snap Fix Glazing Bars or Alukap-XR Aluminium Glazing Bars.

To install your Alukap-XR Fixing buttons correctly follow the below installation steps...

How to Install Polycarbonate Roofing Sheet fixings - Steps:

  1. Match the colour of the Alukap®-XR Fixing buttons to the colour of your roof glazing bars, white or brown.
  1. Before installing, always check that you are wearing the appropriate PPE required for your project to avoid injury
  1. Drill an oversized hole in your Axiome Polycarbonate Roofing Sheets at the fixing locations using a 12mm HSS drill bit (Note: any holes should be approx. 2mm bigger than the width of Fixing Button shaft to allow for any expansion)
  1. Cut off the tag connecting the small Fixing Button top cap and keep to one side for use later in the installation
  1. Pop out the middle foam circle in the foam washers and then add to the fixing button base.
  1. Once the Foam washers have been added place the Alukap-XR Fixing Buttons in position
  1. Using the screw provided, screw down the fixing button making sure there is a firm seal on the glazing sheets
  1. Finally, snap on the small top cap you saved earlier to complete!


Common Questions about Polycarbonate Sheet Fixings

How many Fixing Buttons are required per polycarbonate sheet?

The quantity of polycarbonate fixings required on a roof can vary depending on a range of different factors including the roof structure, sheet sizes, location exposure and more!

Fixing buttons are only required on cross purlins where your rafter centres are quite wide, 1 metre span plus approximately, so you will need a few for each purlin.

What colours are Fixing Buttons available in?

We manufacture Alukap®-XR Roof Fixing buttons in white and brown colour options. We do not manufacture fixing buttons in bespoke colours as for a bespoke coloured roof we would strongly suggest not using fixing buttons and rather keeping rafter spacings at a sensible level.

Are Fixing Buttons only designed for use with timber purlins?

Alukap®-XR Fixing Buttons are designed primarily for use with timber purlins and so are supplied with timber screws to suit; however, they can be used with any material purlin, steel, aluminium and more, by simply swapping out the screws for your own bespoke screws that are suitable for your purlin material.

Are different polycarbonate sheet fixings required with different thicknesses of twinwall and multiwall polycarbonate sheets?

No, our fixings are suitable for a wide range of Axiome® Polycarbonate Roof Sheet thicknesses, from 10mm to 35mm.

If you require longer screws for your roof you can simply source these from a local hardware store and swap them over.

Although not designed for use with 4 or 6mm polycarbonate sheets because those thicknesses tend not to be used for roofing applications, our polycarbonate sheet fixings can be used if needed by simply trimming the fixing button shaft down. This can be done with a hacksaw or similar tool.


Please Note: The installation of fixing buttons is not necessarily recommended for every roof, due to the risk of condensation issues when installed, even correctly, and so should only be installed where the roof length or width requires. Condensation arising from fixing button installation is an accepted phenomenon due to the installation process on penetrating the middle of the sheet’s flutes.

Have a question about fixing polycarbonate sheets?

Feel free to leave a comment question below and we'll respond publicly to help any other DIYers with the same question!

Alternatively, chat with our product experts on our Live Chat with any unanswered questions you have.


Clear Amber Shop Team

Clear Amber Shop Team

(updated) Thanks John, great question! When using silicone with Axiome Polycarbonate Roofing Sheets you should use our Securbond Sealant. This is designed to work with our Axiome Sheets without attacking the surface like other silicones may do.

John Davies

John Davies

Your Axiome multiwall polycarbonate products Installation Guide step 5 advisesrhexapplication of a bead of Axiome compatible sealant. What is this, is it just a transparent external type silicone?

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