How to Work Out How Much Twin Wall Polycarbonate Roofing You Need

Calculate how much polycarbonate roofing

Twin Wall polycarbonate sheets have a very unique flat appearance giving the simplest of structures an expensive finish and clean look. Keep in mind that if you want to use twin wall polycarbonate that you will need to consider the design of your structure first. If you’re building your pergola from scratch, you have the advantage of  spacing your rafters to suit the width of the sheets so that you can’t see any joins in the roofline. The standard width of Sunlite sheets is 980mm wide.

If you’re in the process of designing or having your pergola designed, its advised that you speak to the builder or designer about your intentions to use Sunlite sheets, and ask to have your rafters set at 1000mm centres or less. If you’re re roofing your existing pergola the same logic applies. In most re roofing cases however, you’re going to need to roll up your sleeves and make a few adjustments by way of adding & spacing your rafters to accommodate the sheets.

To work out how many sheets you need is pretty simple. As we mentioned, your rafter spacing needs to be 1000mm centres or less. So if you count the spaces between the rafters on your plans you will be left with the correct number of sheets required.

The sheets are sold at 500mm increments in length. To determine the length you need use the same method covered in our polycarbonate roofing guide. Similar to standard polycarbonate sheets you should allow 50mm extra to fall into your gutter.

Sunlite Sheets are held in place by ‘H’ Bar joiners. There are two types 2 piece & 1 piece.

Both types do the same job, the only difference is the ‘2 piece’ allows you to put the base piece down first, applying the Captive wedge rubbers, then laying the cover joiner over, which clicks into place sandwiching the sheet between, making the installation a little easier if access is a problem.

Then there is also the one piece H bar, which operates on the same concept, this type only allows you to ‘slot’ the sheets in from the side, starting from one end. Before doing this you’ll need to frame the sheet in a rubber gasket , creating a watertight seal to prevent leaks.

Other accessories you will need are end caps, to finish off the top bottom and ends of the sheets. These also require rubber gaskets and end cap locks to hold them in place.

To calculate the fixings you will need you need to use the dimensions of your sheets as a guide. You will need end caps and end cap locks for the length of your structure as well as it’s width (you essentially frame the roof in end caps) you will also need h bar joiners for each join between sheets (should mirror the total length of rafters on your structure (less the end rafters)) You will also need rubber gaskets and stoppers for all edges of all sheets.

Purchase all your roofing requirements from the Softwoods online roofing store.


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