Steel or wood skillion roof for caravan?

[Nate]

Good Morning all, 

I am looking at potentially building a skillion roof free standing shed/structure to put a caravan under. 

I am undecided if I should use steel or wood for the frame. I will be using colourbond steel sheets for the roof. 

I will need it to be 8m x 8m x 3m, would the framing sizes(thickness and such) for a deck work as the roof framing dimensions.

There will be 4 uprights total one on each corner maybe 1m from each end. 

I hope that all makes sense. 
I have put a photo below of similar

Thank you in advance

Nathan 

[EricL]

Hello @Nate

Welcome to the Bunnings Workshop community. Thank you for joining us and sharing your question about which material to use for your skillion roof.

That looks like an excellent project to cover your caravan. I'm so sorry but deck framing dimensions are not applicable for roof framing use. Deck frames are usually made to carry heavy loads, roof framing is built to withstand high winds and harsh weather. 

Using wood is usually a cheaper option. However, it requires more maintenance and upkeep. Using steel is more expensive but there is less maintenance and they tend to last longer. An aluminum carport, for example, is rust, fire, and bug resistant, and only needs occasional cleaning to keep in good order.

If you purchase a garage or carport kit it will save you time having to figure out sizes and dimensions. 

Let me tag our experienced members @JDE and @tom_builds for their recommendations.

If you need more advice or information, please let us know.

Eric

[JDE]

Nate

For a 8m span I would definitely go steel. Have you thought of putting 2 extra supports in it might reduce the size of the metal needed. C purlins or box channel. I agree with Eric a skillion kit carport would save a lot of figuring out and if you want to put it through council which at that size you should it gets around the engineers spec part, just make sure they are included. I recently designed and built a 7,5 x6,5m shed and council insisted on an engineer sign off which ended up costing me $2000- JDE