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Low-level deck over concrete

Backyardtradie
Junior Contributor
Backyardtradie
Backyardtradie
Junior Contributor

Building a low-level deck transformed the look of this outdoor entertaining area.

 

 

StevieB_0-1629354009106.jpeg

 

The project

 

I built a 3800 x 3440mm low-level deck on a concrete slab. The deck meets the house on two sides, with a 120mm clearance on one side and 110mm on the other, so I decided to keep the deck height just above 110mm.

 

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I used 90 x 45 treated Pine joists sitting on galvanised brackets with about 10mm ground clearance. I was planning on using 70 x 45 joists, but MitchellMc suggested using 90 x 45 to stop the timber from flexing.

 

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I ran the joists in the alternate direction to the decking boards with 400mm spacing on the joists to support the timber.

 

Pre-sanding.

 

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Washed.

 

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Oiled using Cutek with a matte finish.

 

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Before and after

 

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How to build a low-level deck

 

A low-level deck can pose a range of potential design and installation problems, with particular challenges around ventilation, drainage, termites and rotting. But it doesn't have to be a difficult project once you take the time to understand the basics of how they are put together.

 

Experienced Bunnings Workshop member Adam Woodhams has created a comprehensive guide to building your own low-level deck which should provide an excellent reference for getting started. 

 

More inspiration for your deck

 

Whether you are building a new deck or rejuvenating an existing one, get inspired by the clever and creative Bunnings Workshop community in our Top 10 most popular deck projects.

 

Comments
cathham
Newbie

That looks great ! 

MitchellMc
Bunnings Team Member
Bunnings Team Member

Welcome to the Bunnings Workshop community @cathham. It's sensational that you've joined us, and wonderful to see you're excited about this project.

 

Let me mention @Backyardtradie so they are alerted to your kind comment.

 

Are you considering building a deck at your own home? Something like this project could really transform the feel of your whole outdoor area. Please let us know if you need any assistance, as our knowledgeable members would all be keen to provide any guidance you need.

 

We look forward to hearing all about your projects and plans around the house and garden and encourage you to let us know anytime you need help or have something to share. You'll find tonnes more inspiration within the community, just like this project, and I can highly recommend reading through our Top 10 most popular deck projects for more ideas.

 

It's great to have you on board.

 

Mitchell

 

ssjolly
Budding Contributor

Great outcome @Backyardtradie

I have a question. I was wondering how did you go about fixing the treated pine next to the wall? and which bolts and nuts did you use to attach the timber to the brackets?
Thanks

 

Backyardtradie
Junior Contributor

@ssjolly  Apologies for the delayed response. Screenshot 2021-09-15 172934.jpg

Backyardtradie
Junior Contributor

@ssjolly I had limitations with Hebel hence had to take the longer path as shown below. If you have Bricks- suggest pre-drilling through the wood and brick wall and using fasteners suggested by @MitchellMc . 

Reach out as you need- I am sure you'll have more questions when you progress with the project. 

Good Luck!!

Beachbox
Junior Contributor

Beautiful job!

shez_89
New Contributor

Hi @Backyardtradie @MitchellMc , 
A noob on this forum but I'm looking to build something very similar to what @Backyardtradie built. I've got an alfresco enclose on three sides. I'm planning to use 90x45 joists and bearers, and am looking to bolt the bearers to the brick walls. There's about a 10mm clearance once all joists and bearers will be installed although wondering if this will be enough (I noticed this being OK on a couple of other discussions). Do have a couple of questions:

* What screws should I use for the angle brackets of the joists to be bolted to the ground? Also, I know I case Dynabolts to bolt the bearers to the brick wall, although what is the recommended length of bolt give I'm using the 90x45.

*What screws should I use for the merbau to be screwed into the frame?

*Is there anything else I need to consider while building the deck? Pain points etc?

 

Cheers

Shez

 

MitchellMc
Bunnings Team Member
Bunnings Team Member

Welcome to the Bunnings Workshop community @shez_89. It's wonderful that you've joined us, and many thanks for your question on deck construction.

 

A 10mm gap under the timber is really the bare minimum. It might allow water to drain, but there will be limited to no airflow under the structure. Time will tell if this becomes an issue that could lead to a premature life span on the deck.  

 

If the ground is concrete, then Dynabolts are also used to fix the joist brackets to the ground. To join the brackets to the joists, you can use Zenith M10 x 40mm Hot Dipped Galvanised Hex Head Coach Screws. You need to space your ledger board off the brick wall, as it can't be placed directly onto the bricks. You can do that with 10mm worth of plastic packers or flashing. Your Dynabolt needs to be 45mm, plus your packers depth and/or flashing and then at least 50mm into the brickwork. You'll likely be looking for something close to a Ramset 12 x 125mm Hex Nut Dynabolt.

 

My recommendation for the screws would be self-drilling stainless steel. They'll save you a tonne of time by not having to pre-drill and countersink every screw hole in the Merbau decking.

 

If you haven't already read through it, @Adam_W's article on How to build a low-level deck is an excellent resource for what to consider when building a deck.

 

Please let me know if you have further questions.

 

Mitchell

 

shez_89
New Contributor

@MitchellMc Thanks a tonne for your advice - really helpful. I didnt come across the packers for brick installs but that was a good tip. Are you able to tell me why these are required? 

 

WIth the joists, would a 70x45 be better to go with in that case to allow another for more airflow?

Also what size angle brackets are advisable to use?

 

Cheers

Shez

MitchellMc
Bunnings Team Member
Bunnings Team Member

Hi @shez_89,

 

There needs to be a gap or flashing between your ledger board and your wall as you'll be generally attaching above the brick walls damp course line. If there is no gap, moisture can be transferred from your deck into the wall. If this then gets into the houses' timberwork, there can be issues.


More airflow is always better, though you'll need more supports for the 70 x 45 as it can't span as far unsupported. A bracket similar to the Wesfab 75 x 75 x 40 Galvinised Angle Bracket should be suitable.

 

Mitchell

 

 

shauny
Junior Contributor

@Backyardtradie Your picture framing, is it a 140mm board, with a board laying on its side with an additional 19mm space before your normal decking boards? I like that feature just inside of the wide board.

Faheem
Budding Contributor

Hi @Backyardtradie , your deck look so professionally done mate. Excellent job! 

i am going to build my own deck as well and need some guidance on the fixings. Whats the name and size of brackets you used to join joists with the concrete slab? And the screws or bolts you used? And the brackets you used to join joist with the beam at the end. 

And i can see you have one frame edging. What should  be gap between the two joists on the edges to support the frame? 

and lastly, i have clearance of 160-170mm. What combination of footings, bearers and joists you recon I should use? 

Thanks mate,

Faheem

 

Faheem
Budding Contributor

Nice work @Backyardtradie. just a quick one. What type of screws or bolts you used to connect the brackets with the concrete slab?

also, Do you have masonry drill? I have a regular 3amp makita drill. Will that work? 

 

 

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