How to build a deck of irregular shape?

[NoClueButTrying]

Hello Helpful People,

I would like to build a deck but the area is of irregular shape. I have not undertaken any such tasks before so I am at a loss. I have attached a layout showing the footing layout made up of a grid of 100x100 timber posts. The regions circled in red are where I I will face problems. Can you please advise how may I support the load in those areas? 

I am a first timer. I would appreciate your patience. Let me know please if more information is needed. Thanks in advance. 

[MitchellMc]

Welcome to the Bunnings Workshop community @NoClueButTrying. It's wonderful to have you join us, and many thanks for your question about deck layout.

The answer is adding more posts and running a joist between them down the diagonal edge of the deck. At the moment, your posts are too far apart. 450mm would be the max span for decking, so I've added the additional posts between yours and then along the edges. Now, you can lay your decking boards and have something to support their ends. In some cases, you can have a small counter-levered section at the edge of the deck where the joist can be unsupported, so this might save you from having to add the additional post in some sections.

Please let me know if you have any questions.

Mitchell
 

[sethwan]

That’s a lot of posts! Are you laying bearers on top of posts and then joists on top of these or are your joists sitting directly on top of posts?

[JacobZ]

Hi @sethwan,

Allow me to tag @NoClueButTrying so they are notified of your question. Hopefully, they will respond shortly.

You can build a deck with either a single-tiered frame, where the joists run in line with the bearers, or a two-tiered frame where the joists sit atop the bearers. The best design to use would come down to the specifics of your deck and your personal preferences.

I'd be happy to help if you were looking for some guidance on a project of your own.

Let me know what you think and if you have further questions, don't hesitate to ask.

Jacob