Finalising Deck Design - Will this stay up?

[JesseS6]

Hi All,

First time designing a deck and keen to get some feedback. Sketch is below.

In green, we have the posts, 100x100mm where the bearers will be set in also.

In Red Bearers – 190x45mm with 1318mm centres.

Joists in blue – 140x45mm with 395mm centres.

Deck it’s self will be 140x19mm Merbau with 4.5mm gaps.

A couple of questions, are there any issues running the Bearers as a single piece of timber? (5620mm)

And similar for the Merbau, any issues using 5700mm lengths cut to size?

The stumps will be 300mm above ground, noting the 190mm bearers will be set into the posts. So there will be 110mm from the bottom of the bearer to the ground, is this an issue? It will be 440mm from ground to bottom of the deck.

[EricL]

Hello @JesseS6 

Your deck design looks well thought out, but there are a few considerations to keep in mind.

For the bearers, using a single 5620mm length is structurally possible, but timber of that length can be prone to warping or sagging over time. Typically, it's better to join two shorter pieces with a staggered overlap (scarf joint or butt joint over posts) to improve stability and ease of handling. If you prefer to use a single length, make sure it’s properly supported and straight.

For the Merbau decking, using 5700mm lengths cut to size is fine, but consider staggering the joins for a more natural look. Long boards tend to expand and contract, so allow for proper gaps and fixings to minimize movement.

Having more space under the deck is always ideal, but a gap of 110mm should allow air to flow under the deck. 

Before you begin, I suggest checking the rules and regulations of your local council in regards to deck size and height limits. 

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.

If you need further assistance, please let us know.

Eric

[Nailbag]

Hi @JesseS6 

Fantastic start to your deck plans. My first thought agrees with @EricL and check with your local council on several points. First, what your legal requirements are for building a deck this size with regards to submitting approved plans for a building permit. And to check specs for spans, and sub-floor materials, fixings and footings. I suspect the span between the footings will be way off the mark in terms of max distance.

Nailbag

[JesseS6]

Hi @Nailbag ,

Regarding the span between footings, the posts are 1773mm centres, and bearers have 1318mm centers. This is within the Span tables, although I could be reading this wrong?

UPDATE

I think I read the span tables wrong. If I add an extra row of posts in, this would bring the bearers max single span to 1330mm (less then 1400mm per span table). Bearers would still have 1318 centres, which I beleive is fine for 140x45mm joists.

Is this more in line with what you meant @Nailbag ?

Thanks

JesseS6

[MitchellMc]

That sounds better, @JesseS6.

Mitchell

[Dave-1]

Morning @JesseS6 

Your plans look great, only thing I can think of to add that the others havnt mentioned is to consider -

- Under deck lighting

- Above deck lighting

- External GPO/powerpoints

- Water. 

Once your deck is down it can still be done, just makes it harder is all.

Dave

[JesseS6]

Thanks @MitchellMc !

I have seen some of your sketches/renders on other posts and am keen to know what software you use? 
They look really good! 

[EricL]

Hi @JesseS6 

Mitchell uses Tinkercad and I use Sketchup for my renders. Both software packages have easy to follow tutorials that will get you up to speed in no time.

Eric

[Nailbag]

Hi @JesseS6 

Yep now you're on track. And also agree with @Dave-1 in considering cable runs for low voltage deck lights and and irrigation tubing while at sub-floor stage

Regards Nailbag