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Building a low-level deck over concrete alfresco

New Contributor

Building a low-level deck over concrete alfresco



I am a first-timer here and would like build my own low-level decking over a concrete alfresco and on concrete front entrance of the house.


I like some advice as to where to start and how to select the decking timber, Joists and the bearer.


1. The dimensions are 300 x 410 with a 50x50 pillar at one corner. The height from the concrete to the home tile level is 140mm.

2. Also, I got a similar concreted floor at the front entrance with the dimensions 450 x 180, with a corner pillar of 70x55  cm. 


What would be the BOM like? I hear different sizes of timber for joists and the decking.


What tools do I require? Do I need drilling on the concrete?


I got a quote of $2950 + GST for the item 1 above and $ 2000 + GST for the item 2, and thought that I could save some money while gaining a valuable experience.


Front of house #1Front of house #1Front of house #2Front of house #2

Any help is much appreciated.





Alfresco #1Alfresco #1Alfresco #2Alfresco #2



Bunnings Team Member
Bunnings Team Member

Re: Questions about building a low-level deck

Hello @Anantha


Welcome to the Bunnings Workshop community. It's wonderful to have you join us, and thank you for sharing your question about your low-level deck.


I'd recommend reading through How to build a low-level deck by @Adam_W. I suggest reading the section "Achieving Clearance". This will give you a good idea of how big your timber frame should be. The timber size for your frame is based on the distance from the bottom of your door rail to the cement floor. I've marked it with a red arrow in your picture below. 


This distance is the key indicator as to what size of timber frame you can put in. For example, if you have a space of 100mm you could use a 70x45 timber frame together with a Merbau decking panel which is 19mm. This will give you a total of 89mm leaving you with a gap of 11mm. Ideally the bigger the gap, the better it is for your deck's air circulation.  


Once you've decided on the size of the timber frame, the rest of the materials you will use will be based on those measurements. I recommend getting pen and paper to draw out a rough sketch of the area so that you can make a plan for the frame. This will also tell you in which direction the decking panels will be facing. I suggest sharing your plan with the community. We can then make recommendations and provide you with advice and information about your low-level deck.


Here is a link for ideas and inspiration: Inspiring low-level deck builds


Here are some amazing low-level deck projects our Workshop members have shared:





Please keep us updated with your progress, we look forward to seeing your decking frame plan.





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New Contributor

Re: How to build a low-level deck

Hi @EricL


Thanks for the kind and detailed reply.

I am still learning, so please understand my ignorance... :smile: 


The distance that you marked on the picture is around 140mm.


Can I use the following:


1. 90 x 45 treated Pine joists sitting on galvanized brackets with about 10mm ground clearance, instead of a 70x45 timber frame. That would take up 100mm.


2. For the decking, instead of Merbau decking panel which is 19mm, can I increase it to a larger size? Say 'Blackbutt Decking 135 x 32mm Standard'? 


Would the above add up to 135mm high, where I can still increase ground clearance by another 5 mm?


I am drafting a plan and will share shortly with the community for any suggestions / recommendations.


Thanks again.





Bunnings Team Member
Bunnings Team Member

Re: How to build a low-level deck

Hi @Anantha,


If you need to achieve an overall height of 140mm, I'd suggest using 140 x 19mm L/M Decking Merbau SpecRite Pre Oiled KD Select90 x 45mm L/M Outdoor Framing MGP10 H3 Treated Pine and Builders Edge 25-40mm Minifoot Pedestal Feet set at 31mm high. The pedestal feet are convenient as you can adjust their height across the deck. You should find that your concrete slabs slope down and away from the house, and as they do, you can raise the feet to keep the deck level.


If you go with your proposed method above, you'd simply connect the joist timber to the galvanised brackets higher up. That will give you the additional 5mm you need.


Please let me know if you have any questions.




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