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Hi all - new here & hoping to maybe have some questions answered regarding some upcoming work im planning at my place!
We have a small backyard that is half concrete/half grass, we are wanting to make the 47m2 space more useable so am planning on decking over the whole thing essentially with a roof covering over the top one day too. Due to poor drainage in the existing grass area I will be starting off by making the drainage sufficient, concreting in the posts, & then covering essentially the whole backyard in blue metal then build the deck over the top. Due to the small height I have (70mm) ontop of the slab I will be using ClickDeck's extra low profile system to make the job possible. Then due to the small clearance in the grass area I have, the deck will be a single-level deck design & I will be leaving the finished height of the ground below much lower than it is currently as to avoid moisture issues under the deck.
My question is, judging by my rough plans I drew up. Am I in the right direction? Do I have too much framing as it does seems like a lot. Although I have based most of my measurements off of others advice but wondering if its overkill.
Essentially plan on concreting in posts, notching out posts to sit joists on & running a joist only system with hangers in place due to my overall clearance.
I'm aware of council requirements on decks & will have to alter the design to suit.
I'll include photo of what the backyard looks like now as well as my plans.
Thanks in advance!
Blake
Welcome to the Bunnings Workshop community @SMUCKY. It's wonderful to have you join us, and many thanks for your question about building a deck.
Your plan looks solid, and it's clear you've put a lot of thought into it. The spans you’ve chosen are within the recommended limits, which is exactly what I would suggest. While it’s possible to push the spans further, this can result in a deck that feels a bit bouncy underfoot, so what you have now should provide a sturdy and stable finish.
Addressing the drainage issues and concreting in the posts sounds like a smart approach, especially with the low clearance and potential moisture concerns. By creating the single-level deck with ample ventilation underneath, you’ll reduce the risk of moisture build-up, which is key for the deck's longevity.
Overall, your layout looks good for the space and conditions you've described. However, remember to approach the council, as if a permit is required, you might also need to employ the services of a draftsperson to create plans for submission. Ultimately, they'll decide if your approach is appropriate.
Please let me know if you have any questions.
Mitchell
Hey thanks for the good info @MitchellMc!
I am thinking about having the edge of the deck along the footpath come down and over and have a fascia board the whole way along. Or potentially even have a step depending once I figure out the height of the existing concrete as it might be a large drop off. My concern though is getting my posts as close to the edge as possible it probably won’t be close enough so my fascia board hangs over the footpath. To do this would I have to double up (or triple) on my bearer closest to the footpath so to give me more overhang from the last post?
And is it easy enough to incorporate steps in? I was thinking having a step in from the edge. Are there any guides on here with maybe something similar?
I have highlighted in orange roughly where my fascia board would overhang and in purple roughly where the step would go.
What do you think?
Cheers
Hi @SMUCKY,
For the overhang, dropping the bearer down below the joists and running them across the top of the bearer to your desired overhang would work. This will create a cantilevered effect that gives you the extra overhang without needing to double or triple up on the bearer. By having the bearer below the joists, you can still ensure structural integrity while allowing the fascia board to extend over the edge.
As for incorporating steps, they can be a little tricky, but nothing too complicated for an experienced D.I.Y.er. The height of the deck and the drop from the existing concrete will determine the size and design of the steps. If you can provide those measurements, I’d be happy to assist you in creating a design for the frame of the steps. Typically, you’ll want the steps to be comfortable to use, with each step’s rise being no more than 190mm, and the tread depth should be around 250mm or so for stability. While I don’t know of any guides specific to step construction for decks on the site, building the frame for steps is very similar to constructing a deck frame—just on a smaller scale and at the appropriate height.
Mitchell
Hi Blake (@SMUCKY),
You could potentially space the posts slightly wider, but I’d recommend referring to a span table to determine the maximum allowable span for the bearers you’re using. The 1200mm spacing you have now is generally what I'd recommend for solid support, but adjusting it could work if it meets the span requirements.
For the footings, determining the exact size is best left to an engineer who can assess the soil type in your area. Typically, a 300 x 300mm hole that’s 450mm deep would be sufficient, and you’d likely need around one and a half bags of concrete per hole. If you're looking to reduce the concrete volume slightly, a 300 x 300 x 300mm hole might work, but that would depend on both soil conditions and the load the posts need to bear.
Mitchell
Hmm okay I think I will stay with the spacing I have in the case. I was recommended to keep the spacing 200mm either side of 1000mm which is what I have done & from what you are saying its probably smart I keep it that way.
It is a new build/area so its mostly clay underneath so not the best, I would say the 450mm depth is probably more suitable like you have mentioned.
Referring back to my response before, if I lower the bearers to fit the joists ontop so I can span the deck out a bit further to be able to do my cantilevar... How far over can I span the joist roughly off the bearer? And how do I fix the joists to the bearer theyre sitting ontop?
We have decided against the step built into the deck as it should be low enough to the existing ground as is but thank you for the offer to help with the plan 
Thanks @MitchellMc
Have a great weekend.
Hi @SMUCKY,
I've just read back through your discussion with @MitchellMc and have a few thoughts about reducing your posts and material costs that might be worth considering.
If you were to use 140 x 45mm H3 Treated Pine Outdoor Framing for your joists as well as your bearers, due to the maximum allowable span of 2600mm while acting as a joist (Hyne Joist Span Table), you can essentially halve the number of posts and bearers around your lawn which in turn will reduce the number of posts, bags of concrete and hangers required as well as making your drainage easier to manage. I've blacked out what you could remove below and still comfortably fit within the allowable spans.
Removing these bearers would also mean your cost for joist hangers would be considerably reduced. Using the 90x45 joists, you would need 136 x Pryda 45 x 90mm Joist Hangers which would cost $340.00 if purchased individually (there is a slight reduction if purchased in pack quantities). Using 140x45 joists, you will need 68 x Pryda 45 x 140mm Joist Hangers which would cost $221.00 when purchased individually.
I have done some cost analysis in the past which shows that when hangers, fixings, and additional materials are taken into account, while the cost of timber is slightly higher, it usually works out cheaper to use materials that can span further while acting as joists.
If you use a two-tiered frame, Pryda Joist Straps are used to connect the joists and bearers. If you cantilever your joists, the maximum I would suggest without consultation with an engineer is 300mm.
Let me know what you think and if you have further questions, please don't hesitate to ask.
Jacob
Hi @JacobZ thanks for the response!
Was just doing a bit more of a thorough calculation today on material and yeah it did add up a fair bit so reducing cost would be great. I have actually rotated my layout 90 degrees now as we are going to run the EkoDeck in the opposite direction. Due to the sizes that the boards come in also I am going to have to install some breaker boards so will have to adjust my framing to suit also. I will sketch up some new drawings now with the changes you have suggested if the span table says the bigger gaps will suffice with the larger joists.
Thanks for the info on the hangers, joist straps & the overhang.
I was looking at lengths that the bearers coming in and because the max length I can get them is 6m, I'm wondering what is the best way to join bearers in a single length if I am notching out my posts? Can I just butt 2 bearers onto the one post and use a tie in strap to hold them together?
I am also struggling though to figure out some stuff with the ClickDeck framing. Where the breaker boards go I will need to reinforce them with noggins but I am unsure if that is an option with this type of framing system. Or even if the EkoDeck will be compatible with the ClickDeck frame? I am also trying to figure out how I can get the joists to overhang the edge of the existing concrete slab as to give me the cantilevar so I can have my fascia board. I have figured out that issue with Mitchell's response earlier for the timber framing, just not the aluminium framing!
Ill attach my revised plans that you can see more of what I mean with the clickdeck.
Will also make changes now with what you've suggested and see where that gets me.
Thanks!
Blake
