How to build deck using builders edge pedestals?

[sharkj]

looking at building composite decking in backyard.

Want to use builders edge adj pedestals, if use size bigfoot xl and use bearers 145x45 then can space feet at 1500mm on each bearer when joists are 450mm spaced.

But question is do i need also need feet on every joist also at 1500mm apart ?

figure A or B?

[JacobZ]

Hi @sharkj,

Welcome to the Bunnings Workshop community and thank you for your question.

You could use the orientation shown in Figure A.

Bearers need to sit on posts or pedestals, while joists can be supported exclusively by bearers as long as there is a structural connection between the two, which can be created by using joist hangers with Connector Screws. 

If you are using 140x45mm framing, then the pedestals would need to be spaced at no more than 1400mm apart. This can be seen in the Hyne Timber Bearer Span Table.

If you also use 140x45 framing for your joists, then your bearers could be spaced 2600mm apart, which would mean the spacing between your bearers can be increased if you would like to. This can be seen in the Hyne Timber Joist Span Table.

A deck based on the maximum allowable spans of 140x45 timber can be seen in How to understand deck span tables. There is also some good information that should help to clarify.

Let me know what you think, and if you have further questions, please don't hesitate to ask. I am more than happy to help.

Jacob

[sharkj]

thank you JacobZ

Had planned on 140x45 bearers and 90x45 joists, 

so pedestals then 1400mm apart on each bearer for support and bearers 1400mm span apart, that looks right doesn't it?

Will look at you option but 140x45 a lot more pricey and since joists every 450mm probably will work out more even though less bearers needed is 2600mm apart 

[sharkj]

so joists don't need to sit on top of bearers necessarily, they can be built in flush with the bearers using joist hangers and the supported bearer is still taking the weight?  (as per picture in - How to understand deck spans - link attached)

[JacobZ]

Hi @sharkj,

Yep, those spans are correct if you use 140x45 for the bearers and 90x45 for the joists.

Yes, that is correct, joists don't need to sit on bearers as long as you use a joist hanger. They reduce the height needed to build a deck greatly, and you'd find most carpenters build decks in this way nowadays.

Let me know if you have any further questions.

Jacob

[sharkj]

Another option

If i were to use sleepers instead- heavy work  

50x200 H4 - which aren't too expensive

then using data for 190x 45 bearers and joists - similar size but under estimating so ok

I could span bearers with pedestal feet every 1800mm

I could run joist spans 3600mm

Build flush with hangers etc so not sitting on top 

Correct?

[EricL]

Hello @sharkj 

Sleepers are not typically designed to act as joists or structural bearers in decking. They lack the necessary span strength and may not meet building code requirements for load-bearing structures. Decking systems require a properly engineered frame of bearers and joists to ensure safe support for foot traffic and furniture. In many Australian states, building codes and standards (like AS 1684 or AS 2870) require decks, even low ones, to be constructed to specific structural guidelines. Sleepers don’t meet those standards for spacing, fixing, or uplift resistance, and using them could result in a non-compliant and unsafe structure. Not all sleepers are dynamically stable and twist, warp or shear as it begins to dry off and weather. Structurally rated timber will often be very stable and will have minimal movement as it ages.

I suggest having a quick look at this discussion - Low-level composite deck over concrete and soil by @oninpena. This is an excellent example of a single low-level deck frame built from 90x45 H3 framing timber and supported with angle brackets and pedestal feet. I also recommend having a look at these guides How to build a low-level deck by @Adam_W and How to build a deck by @MitchellMc.

If you need further assistance, please let us know.

Eric