How to build low-level deck over slab and soil?

Question

Hello team!

I'm an absolutely novice in all and anything building, but now that I have my very own house, I can finally start addressing my jealousy and do stuff around the house, starting with a project of building a wooden deck over a slab and soil. The slab is a 3x3 meters and about 25cm height. I would like to have a deck over it of about 4x4 or slightly less (maybe 3.7 x 3.7 roughly).

This would 100% be much better done by a professional, but would take away all of the fun, so I would like to do it myself, even if it takes several weekends.

My starting point has been to use ChatGPT to give me inspiration and visualise how it would look like, which was a check, second (wife approval) was also a check, so now it's time to plan and build.

First questions that arouse were:

* Should I try to extend the slab to the desired length? According to ChatGPT it would require an awful lot of concrete, and I'm not sure if it's worth it.
* Should I try to dig some holes in the soiled area and put some poles to support the "external" part of the deck that won't be supported by the slab?
* Should I try to include a step or would it work to have pavers surrounding the deck?

The photos below are (1) what I currently have and (2) what is the desired state. I have also uploaded these as a comment to a similar question here:

How to build deck framing over concrete and soil? - Bunnings Workshop community

All and any advice would be greatly appreciated. Thanks in advance, team!

Cheers,

Ed.

eponzoni · Answer

Hi @EricL thank you so much for the well detailed and comprehensive response, mate! Love your work! I will get started on it over the weekend and will make sure to come back here and to your directly to thank you and share the end result.

Thank you very, very much!

Cheers,

Ed.

EricL · Answer

Hello @eponzoni

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your decking project.

I suggest having a quick look at these guides - How to build a low-level deck by @Adam_W and How to build a deck by @MitchellMc. These will give you a general idea of what you need to take into consideration when you start drawing up your decking frame. I also recommend having a look at this featured discussion - Low-level composite deck over concrete and soil by @oninpena. It's an excellent example of a single level deck that's built over concrete and soil.

Generally speaking, you can use timber posts,

https://www.bunnings.com.au/builders-edge-70-170mm-bigfoot-xl-pedestal-feet_p2450075

and

https://www.bunnings.com.au/tuffblock-300-x-300-x-90mm-instant-foundation-system-deck-support_p2410345

. These are some of the options available to you when it comes to supporting your timber decking frame.

To answer your questions:

* I propose building a large timber decking frame and using a footing system rather than extending your concrete base. It's easier to install and will not cost you as much as adding more concrete to your existing base.
* Examine the options available to you, gather as much information as you can about what supporting system to use under your deck.
* Both options are viable and it all depends on what you prefer.

I also suggest having a look at the Bunnings deck building guide along with the Decking Planner on the Bunnings website.

* How to plan out your deck
* How to set out a deck
* How to install stumps
* How to install bearers
* How to install joists
* How to lay decking
* How to add a step to your deck.

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

Eric