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Building a low-level deck over concrete

MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: building a deck

@DIYImpressions,

 

The decking is laid perpendicular (at right angles) to your joists. The joists are spaced every 450mm. The decking screws into the joists, so the screw intervals would be 450mm. Those lines of screws in the top image follow the joists placed underneath. You put two screws at every joist along the length of the decking.

 

You can use Pryda Joist Hanger Stainless Steel Suits 45 x 90mm to mount the horizontal joist to the vertical joist. These brackets are mounted internally and will leave the horizontal joist plain.

 

The black product could be Protectadeck 45mm x 25m PVC Joist, which protects joists from severe rotting and effectively seals around nails beneath decks. It's used to ensure maximum life and durability of your deck all year round. It is not a necessity, though. If it were a liquid product, it would have been similar to Diggers 4L Eco In-Ground Timber Protecta, which increases the rot resistance of H3 treated timber.

 

Mitchell

 

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EricL
Bunnings Team Member
Bunnings Team Member

Re: building a deck

Hello @DIYImpressions 

 

My apologies for the incorrect product recommendation. I don't know why I was thinking you were going to use Ekodeck. Perhaps, because of its ease of use, it was the first thing that came to mind. However, @MitchellMc's recommendation is the perfect one to use for concealed fixings on a timber deck.

 

Eric 

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DIYImpressions
Junior Contributor

Re: building a deck

Thanks @MitchellMc i will look into tutorials for using Camo pro. 

For Pryda Joist Hanger, which nails will you suggest and two on each side will be enough? 

and what tool should i use to mark the merbau panel at angel so that I can cut for a picture frame look or its just a 45 degree angle? 

CE3C81E1-9196-4729-9387-910FFD565A1B.jpeg



thanks

 

 

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MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: building a deck

@DIYImpressions,

 

You'll use Pryda Timber Connector Nails 35 x 3.15mm to secure the joist hangers. The hangers have twelve holes for securing, and Pryda recommends that you use them all.

 

Provided your deck ends up being perfectly square, then it will be two 45-degree cuts used to make the mitre corners for the picture frame. A try and mitre square will assist with marking those cuts.

 

Mitchell

 

 

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DIYImpressions
Junior Contributor

Re: building a deck

Thanks Guys.

 

@MitchellMc @EricL how do I mount the first and last joist because if I use the the recommended nuts and bolt, it will go pass the joist and I wont be able to mount the merbau deck panels on sides. If you see the picture, red marked circles will have nuts on that side. What should I be using then? 

53DA547C-DE0F-4344-9016-8754CDE6708F.jpeg

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MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: building a deck

You can place the brackets on the inside timber instead, @DIYImpressions. Those two joists' lengths will be screwed together through the spacers. Alternatively, you can just countersink the bolt head or nut into the outside frame timber so it isn't proud of the surface. It won't obstruct you placing the fascia board on then.

 

Mitchell

 

1.png

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DIYImpressions
Junior Contributor

Re: building a deck

@MitchellMc @Considering picture framing with 140mm deck board, what block size I should use between the first two and last two joists? Is a 60mm space size block enough with Zenith 14G x 150mm Timber screws?

 

also at what interval should I put spacer? and required timber screws?

 

I have now finalized the layout which looks like below. Can you review and comment? I have decided not to use a horizontal joist and added more angle brackets on both sides of the joist to prevent twisting. Is that ok?Screen Shot 2021-12-01 at 1.15.16 pm.png

And with angle brackets, do I have to use Ramset 12 x 60mm DynaBolt Plus Hex Nut Bolt and Ramset 12 x 75mm Galvanised AnkaScrew Masonry Anchor together? Dynabolt already comes with a bolt?

 

I also did a test by drilling a hole on my concrete floor and can't go beyond 70mm. Is 75mm a standard or I can go lower than that? 

Thanks

Thanks

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EricL
Bunnings Team Member
Bunnings Team Member

Re: building a deck

Hello @DIYImpressions

 

The best way to calculate this is to place your 140mm decking panel on top of your frame where the first two joists will be installed for the picture frame. Taking into account the overhang of the first deck panel to cover the top of the fascia, this will be your point of reference where the second joist will be put in. It may be necessary to adjust the size of your timber spacer so that the second joist will come out far enough so that you can anchor the start of the decking panel to the second joist. You'll have to do the same for the other end. I hope that makes sense. As for the interval of spacers, I recommend putting them every half meter. However, if you install them in a vertical fashion, I suggest putting them in every 300mm.  

 

If you need more assistance, please let us know.

 

Eric

 

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EricL
Bunnings Team Member
Bunnings Team Member

Re: building a deck

Hello @DIYImpressions

 

My apologies I didn't see your other questions past the drawing. It's good that you've added more brackets to prevent the joist from twisting. I'm a firm believer in over-engineering. I recommend adding one more bracket so that they will be spaced every 600mm.  Looking at your drawing it seems you're installing them alternately from one side to the other. This is a great way to do it and provides better support for the timber. If you can't drill past 75mm, I suggest using Ramset 10 x 60mm Galvanised AnkaScrew Masonry Anchor in conjunction with a Zenith M10 Hot Dipped Galvanised Washer. Please note that you will only use the AnkaScrew's on the outer edge of the cement base. Using a Dynabolt so close to the edge of your cement base may crack or rupture it.

 

Please keep us updated with your progress, we look forward to the start of your low-level deck.

 

Eric

 

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DIYImpressions
Junior Contributor

Re: building a deck

HI @EricL 

 

initially i understood that i have to use AnkaScrew all over the place. So can you confirm I have understood it correct now that

 

- 60mm Anka Screws with the M10 washer on the outer edges

- All the remaining angles brackets will be mounted with DynaBolt 65mm. Can I use a smaller size and is a washer required?

- Do I still use the washer when mounting the joist with the bracket?

 

Updated diagram:

Screen Shot 2021-12-01 at 6.57.33 pm.png

Thanks

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