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Building a low level deck - How to choose the right materials?

I'm planning to build a low-to-the-ground deck near my swimming pool, and I'm all about using timber that's good for being close to the ground. I know people usually go for 2 pieces of 90x45 timbers for the bearers, but I found this H4-rated 90x90 on the Bunnings site.

https://www.bunnings.com.au/90-x-90mm-3-6m-post-f7-h4-treated-pine-premium-kd_p8422821

Can I swap it for the 2x 90x45?

I get that laminated timber is usually sturdier, but those 90x45 ones aren't H4. And if I use the 90x90, to keep the deck solid (no bouncy), what's the max span I should aim for with the bearers and joists?

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Comments

Jewelleryrescue

Hi @hket2868

You can use 45 x 90 mm timbers and make a box shape add more 45 x90mm every 500mm spacing approx to support top decking.

H4 is better close to wet grounds or lift H3 on to bricks etc.

Place this box structure on top of brickes etc to get correct deck height you want and keep it out of the dirt and wet,

MitchellMc

Welcome to the Bunnings Workshop community @hket2868. It's wonderful to have you join us, and many thanks for your question about decking timbers.

I can't see any reason why you couldn't use that post, as it's structurally rated. For a single length of 90 x 45mm, our members typically space their supports at 1000mm increments, so for 90 x 90mm, I suspect you'd be fine with 1500mm. You'll find it difficult to establish the maximum span using this timber as it's not normally used for this purpose. The max span would likely be around 2000mm, but I like to recommend a span well within the max, as at max span you can end up with a bouncy deck.

If you use 90 x 45mm timber for your joists, you'll need bearers every 1000mm, and the joists get spaced at 450mm centres on the bearers.

Please let me know if you have any questions.

Mitchell

Jason

Hi @hket2868,

Just checking in to see how your deck project is progressing. I trust the advice you received was helpful.

Please don't hesitate to post anytime you need a hand. We're also looking forward to seeing updates as the deck takes shape.

Thanks,

Jason

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