Great to be a part of this community. I'm a novice and need all the help I can get. I'm planning on building a 7x5m deck in our backyard and as you can see there is a concrete slab right around the house (Apologies for the clutter). I've drawn up a plan and was wondering if I'm heading in the right direction. I stumbled upon the L-brackets in one of the other discussions and wanted to know if this would work for me. I will have bearers in the dirt area and the joists would sit on the bearer with an L shape bracket. I'm trying to do the same on the concrete as I only have 60mm clearance from the concrete slab to the door ledge. Any advice would be much appreciated.
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Welcome to the Bunnings Workshop community @sankhadlt. It's fantastic to have you join us, and many thanks for sharing your project.
It appears you might have calculated in a few too many joists over that five-meter span. Ideally, you'd be looking for a joist every 45cm or so. For the five meters, you'll need approx 11 joists, not the 18 pictured.
L brackets would be a perfect way to mount your joists above the concreted area and allow air-flow under the structure.
I look forward to following along with your project and offering assistance as you go. Please feel free to let me know if you have any questions.
Thanks for the quick response and advice on Joists spacing. Duly noted. My only concern is that I only have 60mm height to work with on the concrete slab as I intend to have the decking run flush with the house floor. Most people have used a 140mm joists and if I put a 140mm my deck will be well above the house floor considering the decking boards would go on top of this as well. Hope this make sense. What can I do to make sure the concrete slab component does not exceed 60mm.
To work out your possible options for the concrete area, you'll need to remove the 19mm decking board thickness from the 60mm. That leaves you with 41mm to have both timber joists and a gap for water runoff and airflow. The minimum working height would generally be 74mm, which includes 10mm for water runoff under the joist, 45mm for a joist laid on its side and the 19mm decking board. If you were to have your decking flush with the actual door instead of the tiles, then you could achieve this 74mm. You might have to do some custom timber work to fix the decking over the tiled area where joists can't support it.
Please let me know if you have any questions.