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How to build a timber deck

Former Community Member

How to build a timber deck

A few members have asked specific questions about Timber Decks

I hope these additional resources and tools provide useful information in your endeavour

I can provide the following

  • A 3D Model that you can edit/modify as you wish in Sketchup (Free software)
  • A PDF of attached image with hyperlinks to the Bunnings price list and to other useful online resources to help you Design, Engineer & Construct (DEC) you project
  • Google sheets, for quantifying & pricing the timber deck
  • Project planning Apps & Tools

Please post back or leave a PM if you require more specific project tools


 Engineering Decking.jpg


Others (To follow) In the Timber Deck Series 

DIY Sceening your Deck

DIY Roofing & Ceiling Your Deck

DIY  Indoor/Outdoor Living (Partial Enclosures)

Please let me know if there is anything else you may want added

Happy 2018




New Contributor

Re: DIY Timber Deck Series

Hi Chris,


Hoping you can help with a deck design.


I'm working from The Australian Decks and Pergolas Construction Manual sold in bunnings, but for the life of me can't make sense of the span tables. Or at least the design I'm coming up with doesn't seem right.


The deck is planned to be 3300 x 4100, Bearers running along the length, joists mounted ontop. The deck is only 500mm of the ground, and doesn't require a DA.


Bearers - 2/90x45 MGP10

Joists - 90 x 45 MGP10

Posts - DINGO 100 x 100 x 900m 6mm Reinforced Concrete Stump (as per the bunnings DIY video series.


The span tables seem to suggest a joist every approx. 1000mm, but every picture I see of a deck seems to have joists at 450mm.


Have attached the drawings fyi (and can provide the span tables in the back if it makes any difference! Any assistance from anyone would be greatly appreciated!!!


Note: the width of the deck has extended some I’ve drawn this. It’s now going to be 3300 wide. 









Community Manager
Community Manager

Re: DIY Timber Deck Series

Welcome to Workshop @marc_s. It's fantastic to have you join the community. I trust you will receive lots of assistance and inspiration from our ever-helpful and clever members for this project and many others in future.


I have tagged Chris (@BIM_Engineer) for you to ensure he sees your question.


Thanks again for joining us and please let me know if you ever need a hand getting the most from the site.



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Former Community Member

Re: DIY Timber Deck Series

@marc_sWelcome to the forum
Unfortunately I am not familiar with that Publication
I would recommend though

For a 4.1m Length x 3.2m  Width deck 

Stump Locations

Width 3 Stumps (2 equal width 1.60m centres)

Length 5 Stump (4 Equal length 1.025 centres)


2/120x35 f5 Structural pine 3.30m long

at 1.025m centres Nailed or bolted together


120x35 f5 Structural pine 4.10m long

at .450 centres for pine Decking or 600 Centres for hardwood decking

The decking generally limits the joist spacings centres either to 300,450,600mm

The current code is AS1684.2 Table 49 & 50 Bearers & Joists Respectively 

Domestic Timber Deck Design for  guide to decking Types,Sizes & Spans

Please leave a PM if you require further info on AS1684 or if you would like a free Sketchup Model

Engineering Decking1.jpg


Re: DIY Timber Deck Series

Hi @BIM_Engineer - thanks so much for this.

Looking at placing an order for timber and the only suppliers I can find in sydney only do either 90x45 or 140x45. I assume that would change the design in terms of spans and number of posts?

The 2/140x45 bearers will be running length ways, I've also decided to use joist hangers and install joists between the bearers rather than on top, due to lack of clearance (only around 500 mm from floor level to ground, so appreciate your thoughts on that as well.

Again, thanks for your help.


Former Community Member

Re: DIY Timber Deck Series

Hi @marc_s
As you have correctly pointed out there are many variations, for materials , sizes, labour, Design, Engineering,Construction,etc,etc
but only one right solution that suits you. 

Regular Browser

Re: DIY Timber Deck Series

Hey mate

i am looking at tackling a deck in my courtyard. My biggest issue is knowing the specs. Am I reading this right that you offer to draw up some plans for the space, including where to put posts etc

if so I can send through my dimensions. 

Thanks in advance mate 


Community Manager
Community Manager

Re: DIY Timber Deck Series

Welcome to Workshop @davehendo. It's great to have you join us. We are looking forward to seeing how your deck project progresses. 


I will tag @BIM_Engineer for you so he is alerted to your question. 


Feel free to post whenever you need a hand or have a new project to share. And please let me know if you ever need help getting the most from the site. 




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Former Community Member

Re: DIY Timber Deck Series

Hey Hendo
Nice, How about some photos and more info?.. the more info you put up the better the answer.. general info to start off here
-You can find Specs & Details in the relevant Australian Standards and googling images, respectively
-Check with your local Authority as some low decks may not require Planning & Building permits
-try doing a rough sketch design either by hand or using Sketchup 3D , content is also available on Sketchup Warehouse
-States also have differing regulations regarding Engineering Certification & Calculation requirements
I am a big fan of DIY & Design,Engineering & Construction (DEC) automation... unfortunately there are regulations in play
BTW, whats gets put up also helps others

Former Community Member

Re: DIY Timber Deck Series

Thanks for sharing Bala

Timber Deck.png

Re: DIY Timber Deck Series

The step downThe step downarea to be deckedarea to be deckedplan of attack!plan of attack!Hello and Merry Christmas to all,
As you can see I am a newbie :smile: but I will be asking many questions as I am about to endeavor in building a deck over existing concrete slab and around the back of the house over earth and concrete slabs ( when I can work out how to upload photos to this thread rather than start a new thread I will)
I have fare idea on what I have to do but any advice would be greatly appreciated!
I need to build the deck to eliminate the 140mm step down as my mother is having a difficult time doing so and budget is very tight as I am on a carers pension! I don't mind getting down and dirty :smile:
the area I have to sort is 7270 x 2660 , the existing slab slopes away from the house at approx 3deg .
I intend to run decking length ways using 90mm x 22mm pine board
joists will be 90mm x45mm using concrete bolt screws and window packers to level off! set at 450mm spacing but both ends will be around 405mm gap.
over the section of garden bed in corner I will use 90 x 45 bearers bolted to brick to support joists using joist hangers and 2 stirrups set in concrete and weed mat.
I will be repainting slab a dark grey or black so as not to see it through the gaps in the decking which will be, as advised 4mm - 5mm.
I would appreciate any advice on this project
Cheers Wally

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