Designing a Pergola – With Polycarbonate

We have one of the most extensive range of polycarbonate products in Australia. Our team of experts are second to none and can advise you on the best solution for your project.

Designing a Pergola – With Polycarbonate

16th Feb 2023

Designing PergolaS & PATIOS
With Polycarbonate Roofing

Roofing materials have a HUGE impact on the look and feel of any outdoor space. Trust us. We’ve seen the best AND worst of them. 

When designing a pergola or patio it is important to consider what material you will use for the roof, up front.

Think about the impact it will have on the overall feel of your outdoor space. Carefully consider the practicalities of your roofing material product choice. Read this article full of helpful advice! 

With a little bit of planning, a lot of common problems can be avoided. 

Have a look at this image, it’s so typical of what you will find in modern concept designs. And it looks great at first glance. But fast forward 6, 12, 18, 24 and 36 months and will the owners be happy with its usability?


So often we have customers tell us that they wished they had though more about the roof BEFORE they built their structure.  Often, the ‘Insta’ shots and other design or lifestyle articles (like this one on The Spruce) have images of outdoor structures that may look appealing at first glance, but often prove to be impractical over time for many people.

Some of the comments we’ve had from people who originally opt for the look of an open structure without the protections of roof sheeting are, “We can’t use our beautiful outdoor area if its hot or wet.”, “Our outdoor furniture has weathered so quickly, and our cushions are always wet when we want to use them.”, “Our patio roof is going to have to be modified to make it more practical!”

Yep! In our 25+ years of experience, we’ve seen so many aesthetic trends come and go, but in helping customers construct or fix their patios and pergolas, what we know for sure to be true is that a customer’s satisfaction with their outdoor space all comes down to usable PRACTICALITY. 

This article will cover some of the design features that you may want to consider. We’ll also point out some practical considerations that will surround these choices. We hope that by sharing a little bit of our roofing knowledge, you’ll avoid making some common mistakes in your patio or pergola design. 

Design Features

Open vs Covered Structures

Open structures look great in images. In many cases, actually using them isn’t so practical because they offer very little privacy or protection.
Never fear! With a bit of planning (and good advise from us!) you can have the look you want but make your space useable, sustainable, lasting and low maintenance.
For products that protect while still giving an ‘open’ vibe, see our links to ‘glass-like roofing’: Sunglaze Polycarbonate Roofing, and EZ Glaze Polycarbonate Roofing


It happens. Often, with little warning. If you clicked on the link above or have been scrolling on Instagram you will no doubt notice a definite current trend of open timber structures (often also flat roof structures – we will come back to this later).  If you’re going to build an open structure you need to consider if you’ll be happy for your furniture, yourselves and your guests to get wet when the weather inevitably turns.
Is your outdoor furniture designed to be in full weather (hint: almost none is!). Is your deck material going to require ongoing upkeep more often if exposed to the elements, creating more work for you (answer: yep!)? Is the structure itself going to weather quickly needing costly regular maintenance, or even replacement?
By covering your structure with a polycarbonate roofing, you can negate all of the above problems and prolong the life of your pergola, and the furniture and decking material underneath it. So practical.


Natural lighting is very important for the look, feel and function of any area. This is even more important if your patio adjoins your house.  Polycarbonate roofing comes in a range of colours that range from clear (like glass), to tinted and translucent, for a more diffused and shady option. Carefully consider how much light you want however, because the rule of thumb is that light equals heat!  Does your area face west? Do you want to use it it entertain your guests for your afternoon BBQs? Then you may need to compromise the amount of light you’d like with a product that reduces heat.  Polycarbonate roofing gives you a way to effectively control for light, heat and shade in your patio or pergola.  Importantly, they also stop 99% of UV. Yep!  Even the glass-like clear options. Sun-safe.


Are you looking for an effective way to screen your area? Maybe you need to up your privacy from neighbors that have windows or a balcony overlooking your yard?  Translucent sheets are a great option for this common requirement. They still let the light in, stop the rain  and look great, but they will also provide you with an increased level of privacy. Sensible. 

Flat vs Pitched Roofing

Don’t fall for flat!  Another common theme of the perfect outdoor area ‘Insta image’ at the moment is a flat-topped open structure. Now, a flat roof doesn’t matter if you have a truly open structure. But, if you’ve (sensibly) decided to cover your area (or you think you might in the future), the pitch of your roof matters a LOT! 
If you you do decide to put any type of roof cover on it, a flat roof can cause MAJOR problems. Your roof will inevitably leak, you won’t be able to direct water away from entry points (so you don’t get wet), and a flat roof can also possibly cause problems with local council regulations about collecting water. Having some degree of fall on the roof is important when planning any covered outdoor structure.  Even a slight 5 degree pitch opens up a whole range of trouble-avoiding options. Pitch = perfect! 

Rafters Vs Purlins

‘What on earth?’ I hear you ask, ‘Are rafters and purlins?’ See the image below to easily understand what each is and does…

Roofing Terms for quoting

Some designs may have rafters only or predominantly purlins (sometimes called battens). Sometimes these can be a feature in themselves – like decorative battens!  Almost all polycarbonate roofing products can be installed on purlins, but some will need the purlins closer together and some further apart.  Some polycarbonate products shine the most when installed on rafters only. Here it can be very important to make sure that they are spaced correctly for the product that you choose. We can give your guidance on this. In a nut shell, it does not matter which way you go – with rafters and/or purlins – but it may change which polycarbonate product you’ll have the choice of being able to use on your roof – so it pays to think about it first.


So, with all this knowledge now under your belt, think back to the that first image of that ‘Insta Perfect’ – very beautiful but VERY impractical – pergola design. 

On second glance, you might be thinking about more than just the ‘look’. 

You might be thinking things like: 

  • It offers no rain protection to the beautiful glass doorway into the house? I’ll be forever cleaning them. 
  • I’m going to have to invest in furniture covers or get a wet bottom almost every time I sit on the outdoor furniture in this space – cause they take forever to dry – and there is no covered roof to offer shelter from rain.
  • This structure offers no cooling from afternoon summer sun on the big glass doors. It’s going to let a lot of heat straight into my home, instead of providing a cooling buffer.
  • It offers no UV protection to people, plants or furniture below it.
  • There is no protection for the structure itself – that timber will weather fast andsoon the water will start to cause rot on the joins and end grains. 
  •  The structure is totally flat. That’s going to make it very hard to do a good job when retrofitting a polycarbonate roof covering to fix all the above problems.

But never fear. A look ‘like’ this trendy one (and others), but that also offers a level of protection and practicality, is completely possible. 

If you have a particular look that you like, our expert roofing consultants can, in the vast majority of occasions, suggest a product to suit that look. It’s important to know what you most want from your patio or pergola BEFORE you start building it, so that you can ensure that everything works out the way you want and you achieve a space you are delighted by. 

If you need some advice or guidance – give us a call and we can talk you through which of our polycarbonate products might best be suited for your your design ideas.

Happy pergola and patio planning! 




9 thoughts on “Designing a Pergola – With Polycarbonate

  1. What’s the recommended centres for rafters my pergola will be approx 8m x 3m I was thinking 600mm ?
    I was looking at bronze 8mm ?
    Regards Ash
    Also do you do made to measure with fixing kits edging strips etc?
    What would be the rough cost?

    1. Hi Ashley

      Thanks for the questions.

      It depends on what product you are talking about as a few of them fit this description…

      Give us a call to discuss.

      TEAM PCR


    1. Hi Margaret

      It appears that you may be email from the UK, if so it would be best to speak with a local supplier. If you are in Australia, please give us a call to help work out what we can do to assist.

      Team PCR

    1. Hi Roz

      Yes and no… The NCC does stipulate some min pitches for common profiles/shapes. It will depend on the sheet/profile that you are using.

      In practical terms pitch is also important when using polycarbonates for a few reasons:
      1. You can see through polycarbonates – a good pitch helps natural ‘self cleaning’
      2. Polycarbonates while very strong will have more deflection (sag) this needs to be considered at very low pitches.

      Give us a call if you have more questions.
      Team PCT

  3. Good Afternoon,
    For a pergola what is the minimum pitch , ie., degrees or percent ,using polcarb.
    Regards Gary

    1. Hi Gary

      5 degrees Min will keep all options open. Its good to have a product in mind before building structure as some products can look much better with particular designs. Give us a call to discuss…

      Team PCR

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We have one of the most extensive range of polycarbonate products in Australia. Our team of experts are second to none and can advise you on the best solution for your project.

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