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wanting assistance on a deck frame ive got about 200mm to work with before i have to start excavating,
deck is 3.3m x 8m
wanting frame to be low so there is airflow so bearers and joists are not sitting near ground
can the bearers be something like 90x45 x2 screwed back to back together then bolted/screw to some sort of steel stirup in a concrete footing ( steel footing brackets look to be way slimer then timber footings)
then joists would be say 90x45 every 450mm apart
can i use even 70x45 for joists and h4 square posts for bearers
OR
would it be alright to do single layer frame just using 140x45 timber
Rightio I’ve done some very rough drawings anyone able to check over and assist, what sort of stumps/footings would be suitable etc.
Hello @Trentc
Since you have 200mm to use, I propose doing a quick calculation of space. If you build a single level deck with 90x45 and use standard 19mm decking panels you will have 91mm left. If you were to use Builders Edge 35 - 60mm Smallfoot Pedestal Feet you would need a paver to support it such as the Brighton Masonry 300 x 300 x 50mm Cream Mypave 335 Paver. Which leaves you with 41mm, just enough to fit the pedestal feet.
I suggest having a look at this Featured project - Low-level composite deck over concrete and soil by @oninpena. It's good example of a single level deck that uses pedestal feet. On your drawing I see that you've placed the footing in the gaps between the joist, I suggest putting the pedestal feet on the joist itself to support it. Just as you see it in the featured project I mentioned. I propose adding more detail to your drawing so that you'll have a better idea of spacing.
If you need further assistance, please let us know.
Eric
Hello @Trentc
If you are doing a joist over bearer layout you will be technically using all the space available to you and there will be no air gap for air to circulate under your deck. However, if you did dig deeper to provide that gap, that section now becomes an area where water might get trapped. I've placed an image below to give you an example of how much space a joist over bearer assembly would look like. I propose looking at these guides in regards to planning your decking frame - How to build a low-level deck by @Adam_W and How to build a deck by @MitchellMc.
I recommend having a look at a span table for footing distances as it will depend on your plans and timber size you'll be using. Yes, you can use 100x100 H4 treated fence post as footing stumps. Because of the space constraints, I don't think you'll be able to use galvanized footings for this build.
If you need further assistance, please let us know.
Eric
Now going back to a single level frame I’ve done a quick drawing using all 140x45 would this work?
3 main runs of 140x45 sitting on stumps every 1 meter then 140x45 running between all of them every 450mm.
hope the picture makes sense
Hi @Trentc
This is much better 140x45 plus the thickness of the decking panel which is 19mm gives you 159 which leaves you with 41mm as an air gap under the decking frame. I think it will be necessary to increase the number of footings to support all the short pieces of your decking frame. I also suggest bringing the footings closer to 1200mm for better support. Let me tag my teammate @MitchellMc in case he has a better idea on footings.
If you have any other questions we can help with, please let us know.
Eric
