How to make a slope for Pergola roof?

[michaelsync]

I have a Pargolas similiar to this. 

I want to put a roof on it. 

Do you recommand to use the flat roof https://www.bunnings.com.au/sunlite-10mm-twinwall-x-3-0m-clear-polycarbonate-roofing_p1010590 or this one https://www.bunnings.com.au/suntuf-trimdek-3m-solar-grey-polycarbonate-roofing-sheet_p1010785 or corrugated roof https://www.bunnings.com.au/suntuf-1800-x-660-x-16-beige-cooltop-corrugated-1800mm_p0037610 ? 

The top part of my parlago are flat. I need to make a slope for the roof. I am thinking to put the Batons https://www.bunnings.com.au/42-x-42mm-5-4m-baluster-handrail-h3-pink-pine-fj-primed-losp_p0052850?pr... but they are all same size. Do I need to sand them to get different height? 

Thanks. 

[MitchellMc]

Hi @michaelsync,

Adding a roof to a pergola significantly alters the structure's dynamics, and it’s important to ensure that the pergola can safely handle the additional weight and wind loads. Many prefabricated pergolas are not engineered to support roofs unless explicitly designed for that purpose. Adding a roof without verifying the structure’s capacity could compromise its integrity, especially in high winds. To ensure safety, it’s recommended to consult with a structural engineer or professional before proceeding.

If your pergola is suitable for a roof, polycarbonate sheets are an excellent choice due to their lightweight and durable properties. The Sunlite Twinwall sheets provide a modern aesthetic and good thermal insulation, but they require sturdy framing due to their flexibility. The Trimdek sheets offer a flat, sleek design that’s easy to install and provides UV protection. Alternatively, the Corrugated sheets are lightweight and effective at dispersing water, making them ideal for sloped roofs.

Using treated timber battens to create the necessary slope is a practical approach. However, instead of sanding them to different heights, consider elevating the high end to create a slope down to the low end. Ensure the slope is at least 5 degrees (a 1:12 pitch) to allow proper water runoff. For added durability, secure the battens with corrosion-resistant fixings and ensure the roof sheets are installed according to the manufacturer’s guidelines.

Please let me know if you have any questions.

Mitchell

[michaelsync]

Thank you. Sorry. I missed the notification. 

I bought the structured wood from bunnings. 

Re: >> instead of sanding them to different heights, consider elevating the high end to create a slope down to the low end

I am sorry. Does it mean I lift up one side? put some wood underneath one side? 

I was following this video https://youtu.be/_oK2hhzFs1E?si=CIrvjQp5KghvL5x6 but I don't really understand how she created the slope. Do you have any video or picture? 

[EricL]

Hello @michaelsync 

I watched the video twice and there was no picture of a slope in the guide. It could be included in the kit she purchased. For your project I suggest following Mitchell's advice and elevating the high end to create a slope down to the low end. Ensure the slope is at least 5 degrees (a 1:12 pitch) to allow proper water runoff.

I'm sorry but I don't have a video guide on how to make a slope for a pergola.

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.

If you need further assistance, please let us know.

Eric

[Dave-1]

Afternoon @michaelsync 

That is a nice looking pergolla Have you read the spec sheet from the company that says its ok for a roof to be added? I know the brackets look solid and fastening down to concrete in the ground looks good but when a roof is added to a structure think of it as an umbrella or a trampoline in the wind.

As  @MitchellMc has said pollycarbonite sheets are light, tho still act as an umbrella in regards to "lift" in a storm situation. My pool deck has multiple attachment points and it still I think of it in wind gusts. (you can look at my bookmarks and see the decking projects)

With the fall you are after, think of a 70mm by 35mm picee of timber looking end on. This is placed on top right under your eve standing up (so its 70mm tall) then the middle slat will be placed lying down so its 35mm high, then there is no slat on the lowest side (near the fence) 

This way water will have a slow fall away from the house. I am presuming you have installed all four posts at equal levels and into aq solid deep concrete footing. Oh just a thought, you cant have water fall next tour fence with no guttering. You will need guttering and a downpipe plus factor in where you will funnel the stormwater to travel to.

Dave