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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
Hi @SMUCKY,
Just for ease of understanding, is it possible to get some overall measurements on your revised plan? This will certainly help me double-check everything and see if there's anything that might need adjusting. I have a rough measurement based on your original plan of 6 x 6.4m.
When you need to join bearers, I'd suggest using a half-lap joint directly over the post. Drive a screw down through the top section and one up through the bottom section to lock it in place. You can then also use a knuckleplate on either side of the joint to make it extra strong.
There should be no issues using Ekodeck on either framing system as there are Ekodeck Quickfix systems for both timber and metal joists at a variety of board spacings.
As a proprietary system, the manufacturer of your metal deck framing is likely best equipped to answer your questions. I imagine their installation guide will have information on cantilevers, spans and angle brackets that could be used to solve the issues you are facing with your plan.
I look forward to seeing your revised plans and am happy to help further once you've provided them.
Jacob
Hi @SMUCKY,
Going with timber over the concrete is fine, but you will still need to ensure you fit within the requirements of both the joist and bearer span tables. Reducing the size of the timber will reduce its ability to span, so increased attachment points may be necessary to ensure you don't get a springy deck. Luckily, packers and angle brackets are fairly cheap so increased attachment to the concrete won't blow the budget out too much.
Unfortunately, the span table I've linked to is only related to the joists. The Hyne Bearer Span Table shows that 140x45 MGP10 can only span a maximum of 1400mm between vertical supports (posts or pedestals) while supporting joists at 450mm centres. If you wanted to increase your span to 1800mm, you would need to increase the size of your bearers to 190x45. See below.
I'd suggest contacting your local council for advice on anchoring requirements for decks in your areas. With a deck of this size, it's unlikely you'll be able to use pedestal feet over the grassed areas as they are not physically anchored to a foundation. Decks are subject to uplift, meaning in the event of a strong gust, the deck can essentially act as a big sail, capturing any wind that gets underneath it which can in turn lift and throw the deck causing damage to property, injury to persons or worse. We can still plan out the structure of the deck, but I'd suggest speaking to your council and potentially an engineer to ensure the deck meets anchoring requirements.
I'm more than happy to keep working with you as the plan continues to develop.
Jacob
Okay good too know cheers @JacobZ.
I can attach a ledger board to the garage aswell as have the frame joined to the slab directly tied into the rest of the structure to keep everything secure.
I will attach revised plans so you can see where im upto with what I have in mind.... I may be able to get in another row of pedestals to reduce that span down which isn't the end of the world.
I'm wondering if you have any advice for me, I have some downpipes & services come out from the walls in the 2 top corners of my drawing. I'm hoping to deck essentially right around those but I haven't worked out the best way to ensure I have framing there as well so its supported.
Let me know what you think,
Blake
Hi @SMUCKY,
Thank you for your updated plans, they are coming along nicely.
Attaching to the surrounding structures would certainly help secure your deck in place, but attaching decks to existing structures can introduce loads to that structure that it wasn't designed for. I'd still encourage you to speak with your council before deciding on a method of anchoring your deck. A quick phone call in the planning stage could save you a lot of grief in the future if it's deemed things aren't up to your local council's standards.
The plan looks like it is coming along nicely, the one thing I'll note is that the two rows I have highlighted are the only ones truly acting as bearers.
This is ok as every joist is being supported by a pedestal, but you can reduce the number of pedestals used under these bearers considerably. There's nothing stopping you using this number of pedestals and it would certainly make everything nice and solid, but if you wanted to reduce costs, some pedestals can be removed as long as the spans are in line with the Bearer Span Table that corresponds with your chosen material.
To frame around pipes and services, you can usually just cut the bearer or joist slightly shorter and add some perpendicular blocking. Because of the allowable cantilever and the small size of pipes and services, this would not noticeably affect the structural integrity of the deck.
Let me know what you think, I look forward to the next update.
Jacob
Hi @JacobZ,
I was thinking that once I get the plans to a point where I’m happy with everything I will approach council to see what adjustments I may have to make.
I know it’s a bit funny the way I’ve done it but the reason being is I need the overhang so I can get the frame right up close around the edges, and because I can’t get the pedestals that close due to their size/design, I think it will be easier to set them back this way and be able to do the cantilever out to where I need it. To compensate for the support loss that’s why I have decided to support every joist with the TuffBlocks instead, I know it’s probably overkill but I don’t want to compromise on potentially have a bouncy deck.
Thanks for the tip on blocking around services 
Blake
Hey @JacobZ appreciate the time you’re spending in helping me and responding to my questions.
After you said what you said about minimising tuffblocks I did try revise the plans slightly to see if it was possible because I guess less money in material the better. I ended up shortening the distances between bearers to 1400mm so they are within the span table range now. I also halved the amount of tuffblocks but I’m now skeptical that maybe it’s not enough and that I should just stick with how it was before. To help with the overhangs from the bearers to the adjoining structures I was thinking of bolting them to the structures and using as ledger boards.
Maybe I will just go back to previous design if you think it’s no good? Otherwise if you think it’s okay I’ll have to speak to engineer in regards to adding the extra load bearing on said walls.
Cheers,
Blake
Hi @JacobZ I'm back with more questions! 🤣
So after your last comment I ended up making some tweaks on this design. I changed my mind in wanting to use the ledger boards against the structure so I changed a few things slightly and did my spans better I think but still well within span limits.
I also went ahead because I was curious and did some tweaks on one of the earlier designs I sent to you because I wanted to compare to see which one would be the better design to go for (cost, strength, level of difficulty to build etc).
I was thinking design #2 would be far cheaper in timber & tuffblocks but it only came out at $250 cheaper. Which I did some quick calculations due to the different design of #2, it needs far more joist hangers compared to design #1 which ends up evening out the costs anyways.
*Design numbers are at top of plans.
So I just had some questions to ask that you may have some insight on from your experience.
- Which design do you think is better overall taking into account all factors?
- Would you change their designs in any way to make better/cheaper?
- I have tried to take into account joist hangers for material cost, are there other major material costs I need to take into consideration when comparing the 2 designs? (I know I'll need say screws, nails, joist protection, bitumen paint, etc but have decided not to use these when comparing as I guess they will both be quite similar in quantities).
A note also that on both designs I have left a slight gap along the slab where water will be able to drain out from the concrete and into the ground below where I will have a french drain underneath.
Design #1 would clearly be more structurally sound (in my eyes?), so considering the price difference seems neglibible would I just go with that one?
Look forward to your response!
Thanks again & have a good weekend,
Blake
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