How to build a substructure to put Ekodecking onto?

I am planning to build an outdoor decking on one side of a swim spa. The swim spar will be on the raised concrete slab, see photo. The deck will be between the swim spa and the raised garden, see photo. The decking will be on an uneven concrete base. The deck's dimensions are approximately. 950 mm heigh; 1700 mm wide; 5400 mm long with steps on one end and a step to go into the pool. See attached drawing in red.

I need some advice on how to build the deck substructure and what material to use.

Cheers Andrew Deck dimentions.jpg

Deck location part 1.jpg Steps onto deck on this side of deck

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Comments

EricL

Hello @Rufo

Welcome to the Bunnings Workshop community. It's marvellous to have you join us, and thank you for sharing your question about building a substructure for your ekodeck.

I suggest having a quick look at this guide - How to build a low-level deck by @Adam_W. I just want to double-check the measurements that you've given me. Does the 950mm height include the height of the decking panels? Will the decking frame be uneven as it is 1700mm wide, will it go past the raised concrete base? Is the concrete base 5400mm long?

Because you are building to a height of 950mm, I suggest engaging the services of an engineer to draw you up a decking frame plan. The engineer will also be able to tell if your current concrete floor slab is adequate to be anchored on. If they say no, it will be necessary to cut into the concrete so that your decking post can be buried and concreted into the ground.

The common material used on decking is H3-treated timber framing, the sizes vary depending on how you plan on making the deck. There is 140x45, 90x 45 and 70x45 these sizes can be used together to form a standard frame or a single-level frame. The decking post comes in at 90x90 or 100x100.

Would it be possible for you to do a sketch of the deck you are trying to build? This will give our members a better idea of its layout. We can then make recommendations on what materials to use.

If you have any other questions we can help with, please let us know.

Eric

Rufo

https://www.workshop.bunnings.com.au/discussion/comment/24283#Comment_24283

Hi Eric

Thanks for the fast reply.

The 950mm height includes the height of the decking panels.

The decking frame will be a rectangle at 1700mm x 5400mm, it gos past the raised concrete base, see the drawing.

The concrete base is 6400mm long and the pool will be 300mm in from the side to allow the deck to come up to the pool.

Cheers Andrew

EricL

https://www.workshop.bunnings.com.au/discussion/comment/74788#Comment_74788

Hello @Rufo ( Andrew )

Thank you very much for the confirmation of the sizes and the drawing of the decking plan. Now that I see that the deck is right next to the swimming spa, this is something you'll definitely need to consult with an engineer or decking professional. I believe there are rules and regulations concerning the building of a deck when it's right next to a swimming spa. I suggest having a look at your local council's rules on deck construction next to pools.

Having a registered professional draw up the plans for you means that it is up to code and the plan can be submitted for council approval straight away.

If you need further assistance, please let us know.

Eric

Rufo

https://www.workshop.bunnings.com.au/discussion/comment/74788#Comment_74788

Hi Eric

I have checked council regulations, the structure is under the height and square metre of the deck to require council approval. I mainly need some structural advice on how to frame up the deck substructure.

Cheers Andrew

EricL

https://www.workshop.bunnings.com.au/discussion/comment/101040#Comment_101040

Hello @Rufo ( Andrew )

I suggest having a look at the seven-part series guide from Bunnings - How to plan out your deck. You can also check out this excellent guide - How to build a deck by @MitchellMc. I also recommend looking over the guide I mentioned earlier - How to build a low-level deck by @Adam_W. Once you've had a look at these guides, you'll have a better idea of how to plan your decking frame. Some of the things you'll need to consider are in what direction will the decking panels be laid. Will you be putting a picture frame around your deck? Will you be building a standard frame or a single-level frame?

I suggest making a sketch of your decking frame and if you have any questions about your plan, I'll be more than happy to answer them.

Here is a link for ideas and inspiration: Top 10 most popular deck projects

Here is an excellent decking frame plan shared by one of our Workshop members:

Low-level composite deck on soil and concrete by @nvdshams

If you need further assistance, please let us know.

Eric

Rufo

https://www.workshop.bunnings.com.au/discussion/comment/117424#Comment_117424

The decking frame

Rufo

https://www.workshop.bunnings.com.au/discussion/comment/126933#Comment_126933

I was thinking of using 90x90 bearers, is that too much and can anyone please let me know what joist size I should use.

Cheers Andrew

EricL

https://www.workshop.bunnings.com.au/discussion/comment/133230#Comment_133230

Hi @Rufo (Andrew)

The 90x90 timber size is usually used as posts to hold the frame of the deck. I suggest re-drawing your plan but using 90 x 45 instead. I suggest having a quick look at this featured project - Low-level composite deck over concrete and soil by @oninpena. This project should give you a very good idea of how to plan the decking frame.

If you need further assistance, please let us know.

Eric

Rufo

https://www.workshop.bunnings.com.au/discussion/comment/137119#Comment_137119

Hi Eric

The 90x90 post are going to be used to hold the frame of the deck, are you saying to use posts 90x45 instead?

The projects that you have recommended me to watch are low level decks. My deck is 950 off the ground. Do you have any projects that shows building a deck on posts with sizes of timber used?

Cheers Andrew

EricL

https://www.workshop.bunnings.com.au/discussion/comment/139798#Comment_139798

Hi @Rufo

The other option is to use 140x45 as the bearers and 90x45 as the joist. This would be assembled as a standard decking frame, not as a single level. A good example of this are in these guides - How to install bearers and How to install joists. In this particular instance, the assembly was done in reverse with the 90x45 being doubled up with the 140x45 at the top. If you observe closely you'll see that the bearers are made to sit on top of the posts with straps going around them. So in theory, if the posts were to increase in height the assembly method would still be applicable. But because your deck is quite long, I suggest adding more posts to prevent it from being bouncy.

If you need further assistance, please let me know.

Eric

Rufo

https://www.workshop.bunnings.com.au/discussion/comment/141644#Comment_141644

Hi Eric

Thank you for the information. What distancing would you recommend between posts?

Cheers Andrew

EricL

https://www.workshop.bunnings.com.au/discussion/comment/143033#Comment_143033

Hi @Rufo

Post placement depends on the type of timber you'll be using. There is also the factor of the weight of the materials and the number of people that will be standing on the deck at any one time. I propose a distance of 1 meter per post. I prefer to make conservative recommendations to be on the safe side. I suggest having a look at the "span table" from Hyne timber one of our suppliers. The span is how far the timber can travel in the air before it needs support.

If you need further assistance, please let us know,

Eric

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