Decking frame plan for low-level deck

[DUX]

Hello all, 

Long time reader, first time poster here. 

Hoping to get clarification on a low level deck i plan on installing in the back yard. After much research I have come up with the below:

 
Deck Size: 9140 x 2060

Bearer: 150 x 75 (2 of) - I went with the larger bearer to eliminate need for a third. 

Joist: 120 x 45 (21 of) - at 450 spacing.

Supports: stirrups in cement at 2957 spacing (8 of).

I am looking to be efficient with resources without compromising the integrity overall. 

Thank you in advance. 

[MitchellMc]

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

Is this an elevated deck or low-level? If it's a low-level deck, there's a bit more room to move with the timber selection.

With that deck calculator, you'll find that it produces a plan that falls well within regulations. I'm not getting the same result as you have when I input your specifications, so you might have removed the central bearer it suggests and several stumps. Your 120 x 45mm joists have a max span of 2100mm at 450mm spacing. You're right on the cusp of that, so the calculator suggested the middle bearer.

You'll have difficulty finding those timber sizes as they are not particularly common. You'd likely be better off working with 140 x 45mm and 190 x 45mm. If you were to use those sizes, the results are below. Substantially more posts and bearers are needed than the plan you've produced.

 

Currently, your plan would be fairly light structure-wise, and I suggest you bring it closer to what the calculator produces. It's quite a large deck, so you must get the structure right. You might like to have a read through these helpful guides on How to build your own deck.

Please let me know if you have any questions.

Mitchell

[DUX]

Thank you for your response, Mitchell. Very thorough! 

Its a low level deck, my reasoning for the larger bearers, was to eliminate the central bearer, use less stumps etc. However, I had not thought about availability of timber so will work with your suggestions. 

Thanks again!