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Welcome to the Bunnings Workshop community @simontho. It's great to have you join us, and many thanks for your question about building a deck.
The best plan of attack would be to start putting a plan together based on the many decks contributed by our members. This How to build a low-level deck guide from @Adam_W is also an excellent resource. Check out our Top 10 most popular deck projects and Inspiring low-level deck builds for some ideas.
Once you have an idea of how to build a deck, you can start working out its specifications. A general rule is that the decking boards need to be supported and nailed off every 450mm. Those supports can only span a certain distance depending on their size before they need to be supported/fixed to the ground.
You might like to show us some images of the area and a sketch of your proposed deck. Our knowledgeable members can then point out any obstacles you might run into and provide advice and suggestions on your project.
Please let me know if you have any questions.
Mitchell
Hi Mitchell,
Thank you for the information, it certainly is in line with a low-level deck.
I am looking at 140mm boards running away from the house. Please find attached exel worksheet, the deck is not coloured (white).
There are 2 areas, which join.
Area 1, the biggest it is 3.7 metres x 11.3 metres
Area 2 (photo attached, the exel square represent 100mm x 100mm) is 3.5 x 2.1
Many Thanks, Simon
Many thanks for that additional info and images @simontho.
What details on the specifications are you looking for? I'd be more than happy to answer any questions that you have. Perhaps we could start with how high the deck will be. What's the working height between the substrate to your door sills? That will give me an idea of what timber you can use for the frame.
Unfortunately, I can't see a lot of the text in your images as the resolution isn't great enough. What's the relevance of the complex boxes/framing surrounding the blue area?
Mitchell
Once you remove the thickness of your decking timber from the working height, you'll have 181mm left. You could construct the deck's frame and joists with Treated Pine Outdoor Timber Framing 140 x 45mm fixed directly into the substrate with angled brackets. That will leave you with 40mm under the frame for airflow and drainage. Alternatively, you could use Treated Pine Outdoor Timber Framing 90 x 45mm raised on Builders Edge 70 - 170mm Bigfoot Xl Pedestal Feet. That would give you 91mm for airflow and drainage.
What will you be building these decks upon?
Mitchell
I'm keen to hear what questions you have so I can further assist with your project @simontho.
If you've decided on using wooden stumps, did you need information on how far apart you'll be spacing your joists and, therefore, stumps? Generally, you'd keep these around the 450mm mark as decking boards can get a bit springy after that. Depending on what size joist you decide to go with will affect how often they need to be supported by stumps. The 140 x 45mm timber can span further than the 90 x 45mm timber.
If you're looking for a way to plan out the entire deck structure without adding it to your design, there are a bunch of decking calculators out there which can assist you with this. Most will just need you to input the deck's dimensions, and they'll show you where the stumps and joists should be positioned.
Mitchell
Hi @simontho,
You'd need to decide what timber you are using for the joists before I could help you further. All joists and stump distances are based on the size of timber you are using for the frame. It's then a matter of working out what lengths your timber is capable of spanning. As mentioned previously, a great place to start working out your plan would be by looking through the many deck projects our members have contributed and using similar specifications to them. Alternatively, you can reference the Building Code of Australia or employ the services of an engineer to put some plans together for you.
Once you decide on your joist timber, you'll space them at 450mm centres across your area. Depending on the dimensions of the joists, you'll need to support them at appropriate increments along their length. That could be every metre or so.
Mitchell
