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How to build low-level deck over brick pavers?

Hi All - having never attempted a deck build before I have decided to create a revamped entertaining space for our backyard which is difficult to access but lots of potential. I had a few questions on a low-level, single layered deck over existing brick pavers which transitions to over fake lawn (which will be removed). Currently, as shown in the picture, there is only an 80mm height from brick paver to sliding door height. If I remove the pavers I will have 130mm height to play with but could clear soil to create a minimum height if necessary. I have prepared the plan shown (apologies as it is my first effort) but in need of some advice, before I take a wrecking bar to the pavers (tight access space to backyard means everything by hand)!

1. Is it a viable option to connect bearers to these pavers directly with an 80mm height clearance to sliding door frame and then use post anchors in concrete over the lawn area which falls away towards a garden bed?

2. If not, and I remove the pavers - I have 130mm height to play with. I was planning to use 90 x 90mm H4 bearers to create a frame so that anchors to support the bearers can be buried in concrete. Joist hangers would then be used to connect 90 x 45mm H3 treated pine joists. This would only leave however about 17mm gap between concrete and anchored bearer for ventilation. Composite Ecodeck boards to be used are 23mm. Is this a sensible plan or is there a better alternative (such as strip-bearers laid directly on a gravel bed)?

3. For a low-level deck, is it ok to set a bearer directly into concrete using post anchors and not have them sitting on top of separate buried/anchored posts?

4. If the plan above is the right approach and I remove the pavers, then I have a fair task of digging about 22 post holes for the concrete to connect the bearer anchors to. I have assumed about 1200mm spacing between concrete footings with anchor. I cant find a span table to confirm this - is my approach correct?

Single layer deck planCurrent brick style pavers80mm height clearance current

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Comments

MitchellMc

Welcome to the Bunnings Workshop community @ChaosDecker. It's terrific to have you join us, and many thanks for your question about creating a deck over pavers.

With only 80mm worth of height you'd need to turn your joists on their side so they are only 45mm high. It's best not to do that, as there will be such minimal airflow within the deck that the early onset of decay is guaranteed. It would be best to remove the bricks to get that additional height.

With 130mm of height, you could compact the ground and use Builders Edge 35 - 60mm Smallfoot Pedestal Feet. These feet are adjustable, so they are perfect for levelling your deck. You'd have the feet set at 38mm, a 70 x 45mm joist and the 22mm decking. That gives you your 130mm height. You'll need to support the 70mm joists more often than the 90mm at around 800mm centres, but this method will save you from digging a bunch of holes. Unfortunately, I've just spent some time planning this out for you, and the cost of the feet could make this quite prohibitive. I've included the render in case it assists.

The method you've suggested would most likely work, but given the deck size, I'd first check with your local council to see whether you need to submit plans to them for approval. If so, you'd likely have to take your design to an engineer to have it approved.

Please let me know if you have any questions.

Mitchell

ChaosDecker

https://www.workshop.bunnings.com.au/discussion/comment/34802#Comment_34802

Thank you Mitchell - I really appreciate your reply and the time taken to prepare the render. I will definitely look into the use of the Builders Edge 35 - 60mm Smallfoot Pedestal Feet. There is a small section of the deck undercover - if I was to use the joists on their side (which I appreciate is not ideal) - would you recommend any particular bolt or way of anchoring the joist to the paver? Would it just be a Dunnings Galvanised Angle Bracket with an appropriate dyna bolt?

EricL

https://www.workshop.bunnings.com.au/discussion/comment/79710#Comment_79710

Hello @ChaosDecker

It is possible to use angle brackets, however, I'm afraid drilling into your pavers may not be enough support and there is also the possibility of the pavers splitting in half. I know its extra work, but I suggest removing the pavers for a more secure deck framing.

Due to the size of the of your deck, I also recommend putting in Vinidex 100mm x 20m Socked Slotted Draincoil to facilitate drainage and preventing standing water under your deck.

If you need further assistance, please let us know.

Eric

ChaosDecker

https://www.workshop.bunnings.com.au/discussion/comment/104273#Comment_104273

Thank you @EricL and @MitchellMc - In relation to the above option to use 70 x 45mm joists, could you please confirm:

- what is the correct size joist hanger to use for these?

- for the Builders Edge Pedestal Feet, should these be placed on a concrete paving slab or is it fine to place directly onto compacted ground?

- what screws would you recommend to fix the joists to the Pedestal Feet?

EricL

https://www.workshop.bunnings.com.au/discussion/comment/119218#Comment_119218

Hello @ChaosDecker

We've actually been asked this question before. I suggest having a quick look at this discussion - How to attach 70x45 joints to bearers for low level deck? by @tal_itha. In summary it was recommended to use Buildex 18 - 7 x 150mm Climacoat Star Drive Landscape Screws through the bearer into the end of the joist. Please make sure to drill pilot holes to prevent splitting the timber.

This traditional method of using screws to anchor the joist is actually proven to be stronger than using joist hangers. In regards to screws for the pedestal, I suggest using Zenith 8 - 10 x 30mm Treated Pine Countersunk Head Screws. I often suggest using pavers under the pedestal to help spread the load.

There is a greater possibility of the pedestal foot sinking into the soil even if it compacted. Having the paver serves as a solid base for the pedestal.

If you have any other questions we can help with, please let us know.

Eric

ChaosDecker

https://www.workshop.bunnings.com.au/discussion/comment/128185#Comment_128185

Thans Eric - I have managed to remove additional soil from the site so I now have 150-170mm height to play with (vs the original 130mm). Would you recommend I revert to standard 90 x 45mm joists for the low-level (single structure) deck or would the preference be to stick with 70 x 45mm to prioritise additional ventilation?

If I did change to the use of the more common 90 x 45 H3 treated pine, what would the usual span be for the joists in a typical single level structure? I'm trying to see if this will materially reduce the recommended number of Builders Edge 35 - 60mm Smallfoot Pedestal Feet.

In relation to the use of Ekodeck - I saw a video recently where the builder pre-drills pilot holes for facia board screws with an oversized clearance hole and use of a countersunk drill bit - do you have a particular product from Bunnings tht you would recommend for this task?

Many thanks - ChaosDecker

EricL

https://www.workshop.bunnings.com.au/discussion/comment/134026#Comment_134026

Hi @ChaosDecker

It's good to hear that you've managed to create more space for your deck. A tricky question indeed between using the 90mm or the 70mm framing. If you use the 90mm timber, you'll be able to spread the distance between the pedestal footings to 1000mm. If my calculations are correct, it will conservatively save you 16 pieces of pedestal footing.

However, the drawback of course is that there will be less space for ventilation underneath. You can counteract this by putting a larger gap such as 5mm between your decking panels. This will help with the ventilation under your deck.

In regards to the drill bit, did you by any chance grab a screen shot of the tool they used? There are drill bits with collars and counter sinking bits that help with drilling. Have a look at the Macsim 10g Clever Tool Standard Head - Blister Pack, P&N 10G Quickbit TCT Cut Smart Countersink Drill Bit and the Starborn No.10 Smart-Bit Flat Head Countersink Drill Bit.

If you need further assistance, please let me know.

Eric

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