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Hello, I am planning to build a deck for the first time, and it turned to be a low -level deck. I looked into some posts and YouTube videos to get the basics and came up with a plan. I want someone to check my plan and advise if I am making any major mistakes. I also have a couple of questions.
Basically, I want to extend my tiled alfresco with a deck of size 3220 mm X 3160 mm very similar as shown in the photo below. Since I want to make the deck level with the existing alfresco, I have only 140~150 mm height to work with.
I am thinking of building a floating deck inspired by the video by Mitchell (https://www.youtube.com/watch?v=8pk_KmaL6i4). I am considering TuffBlock (https://www.bunnings.com.au/tuffblock-300-x-300-x-90mm-instant-foundation-system-deck-support_p24103...) or small foot pedestal feet (https://www.bunnings.com.au/builders-edge-35-60mm-smallfoot-pedestal-feet_p2450074) for footing and place joists (90mm X45 mm) directly on them without any bearer. I am leaning towards the small foot because it gives a minimum 35 mm height and its height is adjustable.
Option 1 - TuffBlock: If I use TuffBlock, then I will need a some digging as I need to use 400X400X40 paver + TuffBlock + Joist + deck board, giving me a total height 40+50+90+23 = 203 mm. But currently I have 140~150 mm. I can use roughly the following framing as shown in the ToughBlock installation document. I will need 7 joists and 21 TuffBlocks as shown below. But I will need to work precisely with the height to level the deck with my alfresco floor which I am not very confident about. Any suggestions so that I can be precise in maintaining the deck height level with my alfresco floor?
Option 2 - Small foot: If I use small foot, then the total height will be 40 (paver) + 35 (small foot) + 90 (joist) + 23 (deck board) = 188 mm. I will need a bit digging, but its flexibility is adjustable height. According to Small foot specification documents the 90X45 joist can be up to 500 m apart, so I can use 7 joists as above. But the small foots supporting each joist need to be 400 mm apart, which means I will need 8 foots per joist. So in total I will need 7 X 8 small foots. Is this calculation correct? Or I am making some mistakes as 56 (7x8) small foots seems too many. Do I need to use the 400X400X40 paver under each small foot?
Q1: Since I am not creating a picture frame, I do not need additional piece of timber at both ends of the frame, as shown in Mitchell’s video above, right?
Q2: I do not want to use picture frame and Ekodeck to match my tiled alfresco floor. So I think I will need to use facial board to cover the face and side groove of the Ekodeck board, right?
Q3: I heard that all decks sink a bit after installation. Is that correct? In that case even I build my deck level with my alfresco, will it sink afterwards? It will be not very neat. Any comment/suggestions?
Any other suggestions would be much appreciated. Thanks in advance.
Welcome to the Bunnings Workshop community @diy501. It's marvellous to have you join us, and many thanks for your question about creating a deck.
Either of the options you have outlined will work, and it is clear you have a solid understanding of the fundamentals already. For a low-level deck like this, both TuffBlocks and Smallfoot pedestals are commonly used and suitable, so it really comes down to which trade-offs you are more comfortable with.
With the TuffBlocks, one advantage is that they can sit directly on well-compacted soil, so if you are willing to excavate and properly compact the area using a hand tamper or mechanical compactor, you may not need pavers underneath them at all. That can save you some height and reduce the amount of digging required. The key with this option is taking your time to get the ground level and compacted properly. To maintain a consistent height flush with your alfresco, set up string lines at the finished deck height and measure down from those to your supports. Using line levels on the string or a laser level gives you a flat reference to work from and removes a lot of guesswork.
With the Smallfoot option, your understanding is correct. They do require closer spacing because of their smaller load capacity, which is why the numbers quickly add up. Needing around 56 supports for the whole deck is not unusual for this system. Because they have a small bearing surface, using a 400 x 400 x 40 mm paver under each one is recommended to spread the load and reduce the risk of settlement. The benefit of the Smallfoot system is the adjustability. Once everything is roughly in place, you can fine-tune the height very accurately using a level, which makes it easier to match the alfresco height precisely.
If you are not doing a picture frame, you do not need the extra perimeter joists that are specifically there to support the picture-frame boards. However, because you are not picture framing and are using Ekodeck, you will need a fascia board to cover the exposed ends and side grooves of the decking boards. This is standard practice and will give you a clean, finished look that ties in neatly with the alfresco.
Not all decks sink over time. Settlement only occurs when the soil beneath has not been adequately compacted or if supports are undersized for the load. A well-prepared, well-compacted base can remain stable for many years without noticeable movement. If you build the deck level with your alfresco and take the time to properly prepare the ground, there is no reason to expect it to drop later.
Overall, your plan is well thought out for a first deck, especially given the tight height constraints. Take your time with ground preparation, use string lines or a laser as your reference, and you will be able to achieve a level, neat finish that flows nicely from the alfresco.
Please let me know if you have any questions.
Mitchell
Ideally, all decking should have a clearance of 300mm, whether that's Ekodeck or standard timber @diy501. We've seen plenty of people use Ekodeck at less than 300mm without any issues. As you've pointed out, Ekodeck does specify a minimum of 300mm (but that's only for the Essentials line), and that is a requirement for warranty coverage. However, that is only for over an area with inadequate drainage. If you were to add drainage you can have it as close as 100mm to the ground. The Classic or Designer Series, which can be bought as close as 90mm, without adequate drainage or 40mm with it.
If the area under your deck is especially moist, it could affect the lifetime of the product. That would be the same with timber decking. If you have concerns I'd go with the Classis or Designers Series.
Mitchell
