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Hi everyone,
I want to build a deck of around 14m x 1.3m on one of the sides of my house.
I checked many forums, websites and post here and there. I learned a lot but I still have a lot of doubts. Most of the information out there is about huge decks built in which I guess are cyclonic areas or with extreme weather conditions like snow, etc. I live in NSW and I think a ground-level deck could be somehow much and simpler, with fewer components while remaining robust and compliant with the local standards.
As you can see in the pictures below, the area is next to the neighbor lot. Also, I need to dig out some centimeters (maybe around 20'ish cm) in order to make the deck flush with the terrace and side entrance. Currently, there are 4cm between the terrace level and the soil.
- Do I need to leave a gap between the colorbond fence and the deck?
From my understanding, the classic deck structure has concrete pads, some sort of galvanised stirrup like this, posts, beams, joists and the decking board. In order to make it flush with the terrace, If I use all the above, I will need to remove a lot of dirt .
For instance, I was thinking of using like a 300mx300m concrete pad, galvanised stirrup on top of it and then beams and joists at the same level like the following (sorry for my draft 2d/3d sketch).
What would be the minimum required components for a low-profile deck? Which brackets are appropriate for a low-profile deck without posts?
Providing that I need to remove some dirt next to the fence sleepers (see img below) they used to level up the fence:
- I wonder if it could somehow collapse. What can I do to prevent that?
Last but not least, can someone (@MitchellMc ? 
) help me to calculate the beams/joist and concrete pad needed based on the above deck dimensions?
Cheers,
Tavo
Community manager's note: Check out How to build a low-level deck for expert advice.
@tavo1421 here’s a couple of photos of the substructure of my deck in case it’s helpful. Bearers 140 x 45 H3 treated pine, 300mm half stirrups for stumps, concreted in the ground over the part that wasn’t concrete. I used a plastic adjustable support over the concrete.
finished level is 250mm above ground height to be level with the existing floor
Welcome to the Bunnings Workshop community @tavo1421. It's amazing to have you join us and many thanks for your questions.
It's great to see you've been receiving some fantastic assistance from @pepsp.
I've included a rough plan of how your deck could be constructed. You must check with your local council regarding requirements on building a timber structure that close to a boundary fence. The fence posts are held up by concrete footers and when excavating around those you should take care. Any idea how far you need to dig down? My plan utilises 90 x 45mm H3 timber.
You'll need to investigate what options are available for structural grade H4 timber as it is not readily available. Therefore decks are generally built a certain height above the soil. In @Adam_W's article, he references ways to minimise damage from the soil in close proximity to your timbers.
I look forward to following along with your build and please feel free to ask as many questions as you like. We're here to help.
Mitchell
You could use 90 x 45mm for the entire frame, including joists and bearers @tavo1421.
Determining a footer size is not as simple as just digging a hole and filling it with concrete. A geotechnical engineer needs to take soil samples from the site, subject them to varying tests, and then specify the correct site classification according to Australian Standard AS 2870/2011 - Residential slabs and footings. They will then determine the footer sized required for the build. This process is generally required if you are submitting plans to council for approval.
You could attempt to establish the required size yourself by contacting the council and seeing if they can provide the soil type information in your area. You'd then need to download a copy of Australian Standard AS 2870/2011 to get sizing.
A footer of 350 x 350 x 450mm would be the minimum sized footer for stable sites. You'll find the more reactive the soil type, the larger the footer needs to be. If in doubt, I'd encourage you to employ the services of a qualified professional.
The cardboard tubes are not needed to create an inground footer, and the concrete can be poured directly in the hole. Those tubes are usually used to create circular piers which extend above ground.
Mitchell
