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I'm going to add a deck on to the end of an existing 90mm thick concrete patio, with the deck being installed over sand. The sand section falls away unevenly from the concrete but maybe 100mm over the intended 3m width.
I'm figuring that using posts will be the easiest way to get the deck level but as the ground sits now there is not much depth to play with. My plan is to dig out and down another 200mm and retain that to create some space. At its closest that would put the bottom of the bearers and joists about 180mm the ground.
If I spaced the decking at 5mm is there enough circulation to still get away with H3 timber? Noting that H3 is far easier for me to come by.
I've sized the bearers and joists at 90x45 to maximise the clearance but it creates a bit more work. Basically I'd end up with the frame being a series of 1m x 1m boxes.
My local Council will allow retaining of up to 500mm, sol I could potentially dig further down to make more room. The big downsides to this are its in a spot where I have to dig with a shovel and the retaining becomes far more of an issue.
Anyone have a different way of tackling this? Or does my plan and timber selection look okay?
Hello @Craig_S
Welcome to the Bunnings Workshop community. It's sensational to have you join us and thanks for sharing your question about your decking.
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. You'll get some excellent tips regarding deck framing and building.
Spacing the decking panels at 5mm is ok as it will provide more ventilation. Using H3 treated framing timber is perfectly fine as long as it does not make contact with the soil.
In regards to your framing look, I recommend having a peek at these featured projects - Low-level composite deck over concrete and soil by @oninpena and Low-level composite deck over concrete and soil by @frediynewbie. They are excellent examples of decks using Builders Edge Pedestal Foot and single level deck frame assembly.
I propose drawing your deck framing plan and sharing it with the community. You can also include any questions you might have had while drawing your plans.
If you have any other questions we can help with, please let us know.
Eric
In clarification, its all over sand and I dont think the pedastal feet will have the adjustability to cope with the slope/fall.
This is how I see the posts/bearers/joists laying out
Hi @Craig_S
I propose installing Brighton Masonry 400 x 400 x 40mm Charcoal Mypave Paver as a base for the pedestals. The paver would need to be dug into the sand so that it will be level. This will prevent the pedestal from tilting.
However, I'll leave the choice up to you on which post you would like to use. Just a friendly reminder to visit your local council and check the rules and regulations regarding building a low-level deck. It's important to check if they have size limitations. If you are building something outside those limits a permit might be required.
If you need further assistance, please let us know.
Eric
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