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What blocking for low-profile deck?

Deck designer novice here. I’d really appreciate any feedback on the design, but I’m mainly after advice on blocking. I’m not sure where it’s needed, if at all, or how much to use. This is my first time designing a deck.

It’s a low-profile deck, about 350 mm off the ground. The bearers are doubled-up 150 × 50, the joists are 100 × 50, and the posts will be 125 × 125 mm, with the red ones being anchor piles. The decking will be 140 × 35 mm.

Any advice would be greatly appreciated.

Screenshot 2026-01-20 at 12.40.58 PM.png

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Comments

MitchellMc

Welcome to the Bunnings Workshop community @Hazzy25. It's brilliant to have you join us, and many thanks for your question about designing a deck.

Your plan looks good. Blocking can be added as per the image below. It would continue like that across the whole deck. It might not be a necessity, but it will certainly add to the rigidity of your deck. The only other adjustment I would suggest is minimising your bearing spacing slightly, closer to 1000mm. Although 90 x 45mm can span 1400mm, it can be a bit spoungey and I like to stick closer to 1000mm, even 1200mm would be a big improvement.

Please let me know if you have any questions.

Mitchell

Hazzy25

https://www.workshop.bunnings.com.au/discussion/comment/61876#Comment_61876

Thanks for the insight @MitchellMc! Thanks for the quick response. I’ve updated the design and changed the bearer spacing to 1100 mm, which seems to work better for getting even spacing across the deck.

My next question is whether the ledger would act as a bearer, and if it’s acceptable to have 1100 mm spacing between the ledger and the first bearer.

Also, in your experience, is doubling up all the bearers a bit overkill? Would it be reasonable to use single 150 × 50 bearers for the middle spans, particularly those that don’t sit on anchor piles?

Screenshot 2026-01-20 at 3.22.53 PM.png

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/93433#Comment_93433

If the ledger can be attached to a structural timber member of the house, then that is possible @Hazzy25. Ledgers can not be attached to a brick facade wall.

Here's a helpful guide on How to understand deck span tables. The timber you'll be using is 140 x 45mm. You can see in the tables that a single 140 x 45mm timber can span 1400mm between posts. So, if you did want to use a single bearer instead of the double, you'd need to reduce your post spacing. Anywhere from 1200-1300mm would be fine. It's typically best practise to not build to the maximum span of timbers.

Also, remember to check with your local council regarding planning permission. If they require approval for this deck due to the size and connection to the house, you might need an engineer to prepare this plan for you and specify the timber sizes.

Mitchell

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