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A stunning Merbau deck with picture framing that continues to inspire many other low-level deck projects.
- The project
- Tools and materials
- How to build a low-level deck
- Tips for building a low-level deck
- Other low-level deck projects
The project
Before tackling this deck, Bunnings Workshop member Neo19 had completed a few landscaping projects, including building a raised garden bed, but "nothing major". With the helpful advice of Bunnings Workshop community members, he built a 350cm x 370cm deck with a height of 18cm aligned to his internal floor.
Tools and materials
- 90 x 19mm Merbau decking boards
- 2–3 coats of Feast Watson 10L Natural Traditional Timber Oil
- 10g 50mm square drive ss screws
- Dunnings 65 x 130 x 65 x 5mm M12 Galvanised Angle Bracket
- Zenith M12 x 65mm Hot Dipped Galvanised Hex Head Bolt And Nut
- Ramset 12 x 60mm DynaBolt Plus Hex Nut Bolt
- Builders Edge Assorted Builders Wedge
- Ozito 1600W SDS+ 4J Rotary Hammer Drill Kit
- Starborn No.10 Smart-Bit Flat Head Countersink Drill Bit
Joists were 3500mm long and kept at a maximum of 450mm intervals. Four brackets were used per joist. Due to the length of the deck, it was "impossible to have all spaced exactly the same".
Since the concrete slab wasn't perfectly level, Builders Edge Assorted Builders Wedge was used to adjust the height. "You adjust the height of the joists with these packers and then bolt them to brackets and the packers stay there," says Neo19. "Even if they come loose, it doesn't matter as your joists are already fixed at a certain height to the bracket."
"My clearance from the concrete to the flushed surface was around 180 mm. And I've used 140x45 which gave me around 160 mm. Since the concrete slab wasn't perfectly level, there were some variations in the flushed surface height. I ended up using these builders wedges to adjust the height. They come from 1 mm height onwards."
"For drilling holes into concrete, I initially tried with my Makita cordless hammer drill. My concrete slab was so hard that I gave up after 30 minutes. Went and bought this Rotary Hammer Drill and the job became very easy. If you have that many holes, I'll definitely go with the rotary hammer."
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.
Tips for building a low-level deck
Resident Bunnings D.I.Y. expert Mitch has shared helpful advice with Workshop community members for their low-level decking projects, including:
- Don't cut decking boards to length on a drop saw before laying them. The best method is to fix all your boards onto the deck, mark a straight line and then cut all the boards at the edge of the deck with a circular saw. The finish will be much more aesthetically pleasing.
- Pre-oiling the underside of your decking boards before installation will extend the life of the deck, help prevent cupping and assist in keeping the moisture content of the boards stable. When coating a deck you'll want to liberally apply the oil so it soaks into the boards as the initial coat to the under-side won't last.
- Spray TWA Woodcare 300g Ecoseal Tanalised Timber Treatment on the cut ends of treated pine. It will be green when first sprayed on but the colour will diminish over the course of several weeks.
- A gap under your joists is essential for allowing water to drain. If water is retained under the deck with no drainage, then a moist environment is created where you can expect cupping of boards.
- When planning your deck build, use the Specrite decking calculator to work out how many decking boards and fixings you'll need.
Other low-level deck projects
Inspired by Neo19's deck, Bunnings Workshop member Brendon_B built this 5600mm x 2000mm deck over a pebblecrete slab using 140 x 199mm Merbau.
Bunnings Workshop member Usman built a 11 x 3.5m deck over concrete, with plans to cover the area with bistro blinds from Bunnings.
Hi @MitchellMc Yes the deck's rock solid and looking almost as good as the the day it became ready!
I've started another little deck for the front porch last week however recognizing that I've forgotten some of the little things that I have learned already 
Like it took me a messed up dynabolt to remember that i've vacuumed drilled holes before hammering in a dynabolt.
@MitchellMc you are being very modest there! No doubt, you'll do a spectacular job!
Would be keen to see pictures..
No problem. Happy to share whatever I have learned.
1) Do you have a picture of the structured frame without the merbau?
2) Which part of the angle bracket was mounted on the floor, the smaller part? and did you screw all three holes?
3) The Hex head bolt is self drilled or do you need to drill first and then screw the angle?
Eric has answered these.
4) How did you join two bearers together?
I didn't use any bearers due to low height of the deck.
5) Did you mount any timber between two joists?
Sorry, I couldn't understand this.
6) Is it necessary to leave a gap between concrete and wood? if so then how much gap?
Eric has answered these. What I have learned from this forum is that higher the gap, happier the decking boards.
Apparently moisture the boards are exposed to from underneath, affects its lifespan negatively.
I’m looking at doing something very similar, but have a timber frame house.
in the image attached, would I have to resheet the area missing cladding before abutting the deck frame, or would this opening actually be beneficial for airflow under the deck?
the area currently exposed is the underside of the house extension.
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