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Low-level Merbau deck over concrete slab

Neo19
Experienced Contributor
Neo19
Neo19
Experienced Contributor

A stunning Merbau deck with picture framing that continues to inspire many other low-level deck projects.

 

 

IMG_20191207_141119.jpg

 

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.

 

 

StevieB_0-1622438852635.jpeg

 

Tools and materials

 

 

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.

 

 

  • 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. 

 

 

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.

 

Brendon_B deck2.jpeg

 

Bunnings Workshop member Usman built a 11 x 3.5m deck over concrete, with plans to cover the area with bistro blinds from Bunnings.

 

Usman deck.jpeg

Comments
zacare
New Contributor

Hi @Neo19

how much is the total cost of deck? DIY

EricL
Bunnings Team Member
Bunnings Team Member

Welcome to the Bunnings Workshop community @zacare. It's wonderful to have you join us and share your question about the cost of the decking project.

 

Let me tag @Neo19 to make sure they are made aware of your question. Are you planning your own decking project? If you have any questions, please don't hesitate to post them. Our members would be more than happy to provide advice and information.

 

We look forward to seeing the start of your project.

 

Eric

 

Neo19
Experienced Contributor

@zacare  Sorry it took me a while to get back to you. 

 

I couldn't find my receipts as this was from a couple of years ago. However it costed between $2000-2500 including some tools like rotary hammer drill that I had to purchase. 

 

When are you planning start yours?

 

MitchellMc
Bunnings Team Member
Bunnings Team Member

Hi @Neo19,

 

Many thanks for those additional details. I trust @zacare appreciates them.

 

How's the deck going? Does it look just as good as it did when you built it?

 

Mitchell

 

zacare
New Contributor

Thank you guys, I will start soon 

Neo19
Experienced Contributor

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 :smile:

Like it took me a messed up dynabolt to remember that i've vacuumed drilled holes before hammering in a dynabolt.  

MitchellMc
Bunnings Team Member
Bunnings Team Member

That's fantastic, @Neo19! Keep us updated on your new deck. 

 

I'm in the process of building a deck, and I might need to call on you for some assistance. I hope it turns out looking as impressive as yours.

 

Mitchell

 

nnaa8287
Junior Contributor
Neo19
Experienced Contributor

@MitchellMc you are being very modest there! :smile: No doubt, you'll do a spectacular job!

Would be keen to see pictures..

 

Neo19
Experienced Contributor

@nnaa8287 

 

Hot Dipped Galvanized Hex Head Bolt and nut - For attaching joists to the angle bracket

Dynabolt Plus Hex Nut Bolt - For securing angle brackets to the concrete floor

nnaa8287
Junior Contributor

@Neo19 

 

Thank you for your response. Few more questions

 

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?

4) How did you join two bearers together?

5) Did you mount any timber between two joists?

6) Is it necessary to leave a gap between concrete and wood? if so then how much gap?


Sorry for many questions. Your response will be appreciated.

Thanks,
NR

 

Hot Dipped Galvanized Hex Head Bolt and nut - For attaching joists to the angle bracket

Dynabolt Plus Hex Nut Bolt - For securing angle brackets to the concrete floo

EricL
Bunnings Team Member
Bunnings Team Member

Hi @nnaa8287

 

It sounds like your getting ready to do your decking project. Let me tag @Neo19 so that they are made aware of your questions. For the moment let me try and answer some of your questions. 

 

  • The angle bracket is usually attached with the smaller part on the floor. 
  • You'll need to pre-drill the holes for the Hex head bolt. Make sure to measure the height of your frame before marking your drilling point on the timber.
  • It's ideal to leave a gap between the concrete and wood. The measurement of your timber frame plus the thickness of the decking panel is what needs to be deducted from your available space. If the distance from the bottom of your door to the outside floor for example is 200mm, you remove the timber frame and decking panel thickness, Whatever is left is the gap between concrete and wood.

 

Please keep us updated with your progress, any photos you can provide as you assemble your deck would be much appreciated.

 

If you need further assistance, please let us know.

 

Eric

 

Neo19
Experienced Contributor

@nnaa8287 

 

No problem. Happy to share whatever I have learned. 

 

1) Do you have a picture of the structured frame without the merbau?

 

IMG_20190928_144106.jpg

 

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.   

 

 

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