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Low-level decking plan

Caz11
New Contributor

Low-level decking plan

Hi there. I've been lurking here for several weeks getting ideas for my deck. Just need an opinion on the plan I've come up with. I haven't draw in the joists. The deck would be 8m by 5.3m attached part way on two sides to the house. I'm thinking bearers 140mm x 45mm doubled up and spaced at 1.6m. With galv stirrups every 1.75m. The ledgers attached to the house would be same size as the bearers. Would my joists be ok at 120mm x 45mm? Or could I get away with smaller?
 
I only have around 180mm of height so I need to make single level structure with joist hangers. Also area is currently slabbed. Do you recommend taking them up? Or leaving them there? taking them up will get me a little more clearance underneath and perhaps be better if any moisture gets in? The entire deck is under an existing patio, however weather can still blow in. Any thoughts or advice would be appreciated. Thanks.
 
rough planrough planmessy patio areamessy patio areaheight of deckheight of deck
shauny
Junior Contributor

Re: Low-level decking plan

Oh, that is a good space for a low level deck. You would do fine with using something like the Klevaklip Adjustable Joist supports along your joists.

If I was building in your space I would be going the 145x45mm as your ledger and bearer, and hanging 90x45mm joists off of joist hanger brackets on both boards, and using the Klevaklip brackets along the lengths of your joists and drilling those into your concrete pavers. As long as those pavers have been down a while, they are not moving and are say over 60mm thick, I would drill and dynabolt into them if it was my space.

PS - Are you going to be decking under where you bar fridge is (and raising what looks like a bench top over it?) or just thinking about building out a simple frame under the fridge and raising the top up? 

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EricL
Bunnings Team Member
Bunnings Team Member

Re: Low-level decking plan

Hello @Caz11

 

It's great that you've received fantastic advice from @shauny. His suggestion of using KlevaKlip Concealed Fixing System 137mm ModWood Gal is a fantastic way to quickly build your deck. If we were to add Treated Pine Outdoor Timber Framing 140 x 45mm, plus the thickness of the Ekodeck 137 x 23 x 5400mm Backbeach / Leatherwood Plus Designer Series Composite Decking it would give us a measurement of 163mm. This would leave you with an air gap of 17mm. Ideally, you would want a bigger gap to provide excellent air circulation to prevent moisture damage and mould infestation.

 

However, it is a balancing act between two schools of thought. Using thicker timber produces a stiff decking frame and also means that you will not need as much footing to support the deck. If you were to use timber not as thick such as the Treated Pine Outdoor Timber Framing 90 x 45mm, it would provide you with a larger air gap at the bottom. But, it would also mean that you would need to use more footing supports to prevent the deck from bouncing. 

 

I suggest leaving the slab as it makes for a good base to build the deck on. If the cement base has not shifted in the last seven years and you've not had any flooding in the area it should be sound to build on it. I recommend using the Builders Edge Pedestal Foot Smallfoot 35 - 60mm as a possible deck support option. Whichever material you choose to go with, please keep us updated with your progress. We would be keen to see your deck once it's built.

 

If you need more advice or information, please let us know.

 

Eric

 

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Caz11
New Contributor

Re: Low-level decking plan

Hi Shauny and Eric,

 

Thanks for your reply,.

 

Yes I will be removing that benchtop and bar fridge, (there is also a sink there) and decking underneath, then install new cabinets/benchtop at the new height. I didn't bother putting it in the plan as it just complicates matters, but fairly simple in practice. The window above it opens into the kitchen and is a sliding servery window, will be at the perfect height after decking goes in. 

 

I have to admit I was leaning towards merbau as I personally prefer the look of it and I've calculated that I would require 60 odd boards 5.4 long, in eko deck that's getting pretty expensive and I'm not sure its worth the extra cost over the timber? I'm unfamiliar with the klevaclip system, I'll have to take a look but obviously seems to go hand in hand with composite boards.

 

I actually had a typo its 190mm height which is not much difference though. If I took the slabs up I will gain another 50mm or so for air space and perhaps the sand underneath allows better drainage for the small amount of water that gets in? Im in Perth so the ground is all soil, no clay etc. The patio is completely enclosed on two sides with 2 open sides for weather to come in somewhat. But if I do choose to leave them, the slabs have been down for 20 years plus and not going anywhere.

 

Finally, any idea on how many extra supports and spacing if I used the 90 x 45mm timber? I never really considered this as I though the deck was too large. Even if just my joists can be 90x45 as you suggested Shauny, then the bulk of the deck will have 90mm or so clearance for airflow, only the bearers would be at the lower level. 

 

Too much to think about but I need to take the plunge, wife wants it all done by Christmas... 😒

 

 

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MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: Low-level decking plan

Hi @Caz11,

 

If you were to use 90 x 45mm for the joists, they won't span the current 1.6m and would need to be supported midway. Or, you could add three more bearers, dropping the span to 1m which would be more suitable for them being unsupported. It would be best to reference online timber span tables to work out the maximum unsupported span allowed.

 

Mitchell

 

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Caz11
New Contributor

Re: Low-level decking plan

Thanks @MitchellMc  I'm happy to go with the bigger joists unless you think its worth looking into the 90x45mm in order to get some more clearance underneath? Also do you have a opinion on the slabs under? keep or remove? Thanks.

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Caz11
New Contributor

Re: Low-level decking plan

@shauny 

 

I just found a merbau klevaklip mt90g but cant seem to find them at bunnings, is this what you were referring to? or do you mean the clips that go with the composite boards? Have you ever used these clips with the timber? Just wondering how well they will hold over time. I do like the look of the concealed fixing and they look relatively simple to install but I have only ever done small areas of decking with screw fixings.

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shauny
Junior Contributor

Re: Low-level decking plan

@Caz11 you want these adjustable joist supports which are available via the special

orders desk. Have a read of the Klevaklip website though, very good information on there. 

 

 

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