Just looking for some advice on how to go about building a low level deck off my existing patio.
Would appreciate any step by step instructions, sizing guides and materials needed if possible.
thanks so much!
How much ground clearance from the top of the old patio to the ground do you have?
Welcome to the Bunnings Workshop community @mattgav. It's brilliant that you've joined us, and many thanks for your question about deck construction.
It's great to see @shauny has joined the discussion, and as he's mentioned, knowing the working height is essential.
Once you've got an idea of how the deck will be constructed, it's time to draw up a plan. The first governing factor of building a deck is the height you have to work within. This is even more prevalent when you're building over soil, as there needs to be clearance under the timber. Is your deck is going to be flush with the tiles? If so, you'll need to measure from the surface of the tile down to the ground. What's that measurement currently? From your images, it appears that you're not currently able to build a deck within the available height and a considerable amount of soil needs to be removed over the deck's width. Typically, you'll need 19mm for the decking boards, 90mm for the joists and then a clearance space under the timber. In @Adam_W's article, he goes into detail on what can be done to ensure the surface of the soil is prepared for adequate drainage.
Frame wise, I'd suggest using Treated Pine Outdoor Timber Framing 90 x 45mm around the perimeter and then adding joists at 450mm centres that the decking boards get nailed off to. Once you've removed soil and compacted the ground, you can use pedestal feet to raise the deck. Typically, you'd want a minimum of 100mm between the bottom of the timber and the soil. Any less and you'll quite possibly see the deck prematurely degrade from moisture. You can then clad the sides of the frame with boards to finish. I've included a couple of renders below that I put together for you. The timber used is to scale and it should give you a rough idea of how your deck could be constructed.
That is probably enough to get you started. Please let me know if you have any questions.
Not a huge amount of clearance over soil. I would dig it out a little if it was me. Then Couple of shovel loads of gravel down, compact it and level it off, and then you can use the plastic base feet like Mitchell shows in his diagram.
This deck is a close design idea to how you probably want to do it too.