How to build low level deck over concrete using Ekodeck?

Hello. I am planning to build a deck in my alfresco area using Ecodeck. My space is around 3.1mx6m so I have put together a diagram covering 3090mm x 5096mm. I only have 110mm height from concrete so looking at using 70 x 45mm timber so I can have some space between joist and concrete. Mine is hebel so I have to fix timber to concrete floor.

@MitchellMc / @EricL , can you please help on what I could use to have atleast 10/20 mm space between joist and concrete. I read most of the threads/posts and most of them are using angle bracket. Is there anyway I can escape from drilling holes in concrete? I am thinking of using Minifoot Pedestal Feet. Also, there is no joist hanger for 70x45 so what is my option to connect joist with bearer. I read one of the post and Eric mentioned using construction screws.

So far I have following list of items I need. Appreciate if you can help me with joist hangers, screws etc as this is my first DIY project

Buildex 18 - 7 x 150mm Landscaping Construction Screw
Builders Edge 25-40mm Minifoot Pedestal Feet
70 x 45mm Outdoor Framing H3 Treated Pine 6.0m
Joist tape

subframemeasurementdecking plan

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Comments

EricL

Hello @newB

Welcome to the Bunnings Workshop community. It's sensational to have you join us and thanks for sharing your question about your decking.

It's great that you've had a look at the other discussions regarding low-level decks.

Using the Buildex 18 - 7 x 150mm Climacoat Star Drive Landscape Screw is a traditional method of anchoring joist to the timber frame. However, it is important that pilot holes must be drilled into the timber to prevent them from splitting. I suggest a minimum of two screws for each end of the joist.

In regards to the Builders Edge 25-40mm Minifoot Pedestal Feet. I suggest double checking its application to your deck frame as its minimum height is 25mm. Will this pose an issue in your deck frame assembly?

As to the other items you listed, I don't see any issue with their use on your decking frame. My only other recommendation is that the corners of your deck be anchored to the concrete base. This will prevent the structure from shifting.

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

Eric

newB

https://www.workshop.bunnings.com.au/discussion/comment/38419#Comment_38419

Thank you @EricL.

I thought same about the pedestal feet and I also have angle brackets in my diagram but I am not able to find exact angle bracket that I can use for 70x45 mm joist to have 10mm-20mm space between concrete and joist.

I was trying to reduce amount of holes I need to drill in concrete and I have no idea how many angle bracket I actually need to make the sub frame proper. If you can provide any guidance that would be helpful.

For anchoring I read Ramset 12 x 60mm DynaBolt Plus Hex Nut Bolt in lot of posts so I believe that would be my answer but if you can suggest angle bracket and dyna bolt size that would be super helpful.

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/81387#Comment_81387

Hi @newB,

A 25mm minifoot, 70mm joist and 19mm decking add up to 114mm, above your working height. You'd need to use angle brackets instead of the minifeet and drill into the concrete for each one to secure it with a Dynabolt.

Currently you have your joist supports spaced for joists more similar to 90 x 45mm, which only need to be supported every 1000mm. For 70mm timber you'd need to support it more readily at around 800mm.

Just a word of warning that you are creating an extremely low-level deck and should expect its lifespan to be shortened due to this.

Mitchell

newB

https://www.workshop.bunnings.com.au/discussion/comment/105418#Comment_105418

Thank you @MitchellMc for the reply. Composite decking is 23mm so I have even less space to play with. I saw some videos where they used composite deck material itself to cover the space between concrete and joist because of low level decking. Have you seen this before?

Thanks for the angle bracket and bolt link, those were my missing parts.

I have only 110mm space and I might go 10mm above if I cover the gap between deck and alfresco door.

EricL

https://www.workshop.bunnings.com.au/discussion/comment/119848#Comment_119848

Hi @newB

The good thing about angle brackets is that you have complete control over the installation height of the decking frame. I suggest testing the assembly once you have your materials, it will give you a much better idea of how much space will be left under your deck.

Please keep in mind that making your deck taller than the interior flooring will create a tripping hazard to anyone who is not aware of the flooring height difference.

If you need further assistance, please let us know.

Eric

newB

https://www.workshop.bunnings.com.au/discussion/comment/128627#Comment_128627

Thank you @EricL and @MitchellMc. While looking around for angle brackets in bunnings. I cam across "Macsim 72 x 100 x 10mm Black Packing Shim" so I am thinking of replacing pedestal feet with these shims. Description says it can be used in decking and can support upto 20 tons. PLease let me know if thats not a good idea.

Thinking of attaching them to timber so they don't move.

JacobZ

https://www.workshop.bunnings.com.au/discussion/comment/134241#Comment_134241

Hi @newB,

Unfortunately, that's not a good idea for a couple of reasons.

Macsim 72 x 100 x 10mm Black Packing Shims are often used in decking to account for small height differences, however, they are not designed to be the main support for a deck. There is no way to solidly attach the timber joists to them and there is no adjustability to account for height differences in the slab.

The only way to build a deck as low as you are planning is to attach your joists to the angle brackets that @MitchellMc mentioned earlier.

Unfortunately, some holes in your concrete are necessary if you want to build a deck this low to the concrete.

Let me know if you have any further questions.

Jacob

newB

https://www.workshop.bunnings.com.au/discussion/comment/137815#Comment_137815

Thanks @JacobZ. Noted. So all angle brackets.

JacobZ

https://www.workshop.bunnings.com.au/discussion/comment/140238#Comment_140238

Hi @newB,

Unfortunately, yes.

You need to be able to attach the joists to its support with a screw or bolt. With the packers, there's no real way to do this.

Let me know if you've got any further questions or need any additional assistance, I'm more than happy to help.

Jacob

newB

https://www.workshop.bunnings.com.au/discussion/comment/141984#Comment_141984

Hi @JacobZ, need you suggestion on type of screws I need to screw angle bracket on joist. I did check the "Pryda Timber Connector Screw 12G x 35mm Hex Head" as mentioned in other posts but those are good if I use joist hangers.

After comparing the Pryda screws diameter with angle bracket hole diameter, I think those screws are not right for me. I ended up buying Zenith M10 x 40mm Hot Dipped Galvanised Hex Head Coach Screw suggested by staff.

Are those zenith m10x40mm screws are good for this project ? or can you please suggest the correct one?

I also bought following for subframe

JacobZ

https://www.workshop.bunnings.com.au/discussion/comment/143254#Comment_143254

Hi @newB,

I can't see any issues with the hardware you've selected.

The coach screws you've been recommended are going to be perfectly fine for attaching your brackets to the frame. Just make sure when you're installing them to predrill pilot holes and not over-tighten them. You want them to be firm, but over-tightening them can cause the screw to strip the timber fibres which will reduce their holding power. I'd suggest grabbing a bit of scrap timber and intentionally over-tightening one of the coach screws so you can get an idea of how far to push them before the connection fails. It's pretty easy to tell when to stop if you've over done it before.

Another thing that you might want to consider is grabbing a 5mm long series drill bit for predrilling pilot holes for the Buildex 18 - 7 x 150mm Climacoat Star Drive Landscape Screws. These are a Type 17 screw, which means they are self-drilling, but at the length you've selected, it would still be a good idea to add a nice deep pilot hole to prevent any splitting.

I can't wait to see some progress, keep us updated as your project commences.

If you have any other questions, don't hesitate to ask.

Jacob

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