How to build a deck with roof?

[Whitetees]

I'm building a 3mx3m deck in middle of one of my paddocks and would like some clarification re span table.

My current plan is 3 bearers 140x45 MGP 10 H3 pine with supports at 0,1.5,3

With joists 90x45 at 450 centres.

Posts 100x100.

I will be adding a basic tin roof.

Is my framing adequate? 

[MitchellMc]

Hi @Whitetees,

You’re spot on with what you’ve planned for the deck. The timber sizes and spacing you’ve chosen look good and will work nicely for a 3m x 3m platform.

However, since you’re adding a tin roof, it’s important to clarify whether the posts supporting your deck will also be supporting the roof, or if the roof will be built on its own separate posts. Anytime a roof is attached to a deck, it changes the structural requirements, including the size of the timbers and the footings, because the roof introduces wind loads that need to be safely transferred to the ground.

It’s really worth having an engineer or builder look over your design to confirm that the structure you’re building for the deck can also safely support and anchor the roof. If you can share a few more details about the roof design, such as how it will be attached and its dimensions, that’ll help narrow down what adjustments might be needed for your framing. 

Please let me know if you have any questions.

Mitchell