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Merbau decking over concrete

preechish
New Contributor

Merbau decking over concrete

Hi, hope you're all doing well.

I'm planning to build a 7.2m long ×  4.2m wide 160mm high deck in my backyard over the alfresco which is going to extend all the way to the fence. The dirt area will be levelled with crushed rock and a thin layer of concrete to flush it with the existing concrete floor. 

It would be great if someone can guide me through the installation process like how much gap should be there in between floor and the timber base. What is the best bracket to use which is going to hold the deck sturdy. 

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MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: Merbau Decking Over Concrete

Welcome to the Bunnings Workshop community @preechish. It's great to have you join us and many thanks for your questions.

 

I'd encourage you to start with the guide: How to build a low-level deck by @Adam_W. I trust it will answer most of your questions. There are also many previous discussions on this topic which you should find useful. These can be found through the search bar under "low-level deck".

 

You'll need at least 10mm of clearance underneath your joists for air-flow and drainage. You can pack out under them with shims to establish this gap. Dynabolting the joists down with brackets every meter will secure them to the slab.

 

Do you know how much room you have to work within? This is measured from the slab to the doorsill. If you can let me know this measurement, I can work out some appropriately sized timbers to use.

 

Mitchell

 

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preechish
New Contributor

Re: Merbau Decking Over Concrete

Hi Mitchell , thank you for your reply.  Really helpful. I have attached a photo showing the measurement. Hope this will be helpful. 

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MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: Merbau Decking Over Concrete

Hi @preechish,

 

It appears you have around 170mm to work with. I would suggest you construct the deck's joists from Treated Pine Outdoor Timber Framing 140 x 45mm. This will then allow 19mm for the boards and 11mm for drainage.

 

Mitchell

 

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preechish
New Contributor

Re: Merbau Decking Over Concrete

Hi Mitchell,  could you advise me on the distance between each joists? The total measurement of the deck will be 7.2m long ×4.2m wide.

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MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: Merbau Decking Over Concrete

@preechish,

 

Joists spaced at 445mm would be suitable.

 

Mitchell

 

 

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preechish
New Contributor

Re: Merbau Decking Over Concrete

@Michelle

Thank you.  How many 140mm merbau would I need? Do bunnings have 4.2m or close merbau? I'm planning to do pitcher framing too. Do bunnings cut them to the required measurements and deliver? How much do they charge?

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MitchellMc
Bunnings Team Member
Bunnings Team Member

Re: Merbau Decking Over Concrete

@preechish,

 

It would be around 52 lengths of 4.2 meters or 219L/M. I'd recommend contacting your local store to see what lengths are available. If you are ordering 52 lengths at 4.2 meters, the special order team in-store might order that straight from the manufacturer.

 

Please let me know if you need any assistance contacting your local store for details on availability.

 

Mitchell

 

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