Building a low-level deck transformed the look of this outdoor entertaining area. 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. 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. I ran the joists in the alternate direction to the decking boards with 400mm spacing on the joists to support the timber. Pre-sanding. Washed. Oiled using Cutek with a matte finish. Before and after 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.

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Low-level deck over concrete

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

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.

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.

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

Pre-sanding.

13-Pre sanding.JPG

Washed.

Oiled using Cutek with a matte finish.

Final table.JPG

Before and after

19-Oil coat.JPG

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.

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EricL

Hello @JonoMilne

Welcome to the Bunnings Workshop community. It's wonderful to have you join us.

Thank you for sharing your plans in regards to building a deck. If the concrete pad is sloping away from your home, I don't think it will be an issue building on top of it. It only becomes a bit of a worry if water pools on the slab and directs it back to your house. In order to make sure that the pad is thick enough to support the steel fixings and the decking frame, I suggest digging around a corner of the slab to see how thick it is. If the slab has a thickness of 100mm or more, it will be enough to support the steel fixings and the deck itself.

In regards to damp protection, I suggest putting down builder's plastic and gravel to facilitate drainage. You can also apply Gripset Betta 1L Waterproofing Membrane Bitumen Rubber at the bottom and half the sides of the frame to protect it from moisture. You can also use CAgroup 50mm x 20m Bearer Protector G-Tape to protect the surface of the frame and prevent water from settling on the surface of the timber frame.

As to the masonry waste, it would be best to remove them so that drainage will be free and clear of obstacles.

Let me call on our experienced members @Dave-1, @Nailbag and @Noyade for their recommendations.

If you need further assistance, please let us know.

Eric

JonoMilne

Thanks @Ericv and team. Here are some pics and my layman’s plan. The pics show how the site slopes down gently from the ranchslider and the (previously) buried concrete pad. I think I’ll only need to fit the bearer to the concrete in one place. To the left I can dig down a pile, and to the right the joists will be attached to a ledger board fixed ticthe concrete block foundation of the house.

EricL

Hello @JonoMilne

Thank you for sharing the photos of your proposed deck site. Having seen the layout, I would definitely advise that you build in a nice slope so that water will flow away from the site and not pool or settle at the bottom of your deck. I recommend removing all the masonry waste so that you have a tidy slope under the deck and there will be no hindrance to the flow of water.

Thank you again for sharing your decking frame plans, I tend to over engineer my own projects and would suggest adding an extra post to the long run of 6.3 meters and the one after that.

If you need further assistance, please let us know.

Eric

Nailbag

What a top-notch professional finished job @Backyardtradie 👌Nailbag

Dave-1

Good morning @JonoMilne

The spaceing between the supports I would reduce, I dont like long spans for support as they seem to give a "bounce" to the deck long term.

With the concrete slab unearthed in your excavations 🙂 of course its there! bahahahha Yeah I came across one when I was installing a new path so know the feeling. For you I would leave it and use it for your advantage. As long as it slopes away from the house nad you remve any watse on top it would be fine. I had to remove mine as it would channel water that I didnt not want to happen.

The wall that you are removing, is that retaining any soil? It dosnt look like it is but just in case I would factor the slope in with the edge of your deck and how you will make the transition. (edge board/smaller wall/slope the soil) As long as teh drainage across the are leaves the area and generally funneled somehwer else to be used or taken care of.

Dave

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