How to build a low-level deck over concrete?

[Halima]

Hi team,

Looking to tackle a DIY deck at my parents backyard.

Some details of the space:

- roughly 24m2 (7mx4m)

- Working area is concrete slabbed. Level is variable in certain parts

- Clearance from the internal space to the concrete slab is around 100mm only

- The planned deckspace is covered with an awning - still yet to decide if I'll work around the 4 posts or work right up to it

My thoughts:

- From what I can understand the internal to slab clearance available would be a ideal for 'low profile' deck 

- I'm thinking of using adjustable pedestal feet that will accept the joist frame directly (no bearers). I saw that there's also pedestal feet that will accept blockers

Questions:

- Are gal nails or framing screws better?

- is there any significant feature advantage with pedestal feet that will accept blocker pieces? does it even matter?

- H3 treated wood is reccommended for above ground/outdoor use but what size timber pieces should I be considering and how far apart are the spacing between joists at their centre? I'm sure there's a best practice/building code to this question I'm not familiar with where to start looking

- How do I know the spacing requirements for the pedestal feet?

- Can anyone improve on what I'm thinking of doing or provide other ideas?

thanks in advance!

[EricL]

Hello @Halima 

Welcome to the Bunnings Workshop community. It's sensational to have you join us and thanks for sharing your question about your plan on building a deck.

Please allow me to try and answer some of your questions.

• 100mm is not a lot space to work with, if you were to use 70x35 in combination with standard Merbau decking you would be using 89mm of space leaving you with 11mm as an air gap. There would not be enough space for a pedestal, but you can use angle brackets to hold and support the timber joist.
   
• In my opinion screws are better at framing as they don't easily pull out.
   
• In regards to timber size the space available will dictate the size you can use. You can also look at this guide - How to understand deck span tables. It will give you a general understanding of timber spacing and how certain timber sizes can be used with less support.

I also suggest checking the rules and regulations of your local council regarding low-level decks. There might be rules in regards to size limitations and permits.

If you need further assistance, please let us know.

Eric

[Jason]

Hi @Halima,

Let me also extend a very warm welcome to the Bunnings Workshop community. We are looking forward to seeing your deck project come to life.

In addition to Eric's helpful advice, you should find the guide How to build a low-level deck useful.

Jason

[Halima]

Thanks Eric,

After doing some more reading (guides on here actually!) I noticed there was a low level project that used L brackets - would you be able to suggest any specific bracket? Ive also noted that the short side of the doorway is actually only 90mm. It qickly extends out to 100mm though so would an L bracket in this scenario be appropriate? Im thinking the real challenge is picking a lower profile timber to use as joists.

Would me options become lower profile again if I were to use a hardwood?

[Halima]

Appreciate the link! I came across it shortly after posting and have bookmarked for reading again

[EricL]

Hello @Halima 

There are several sizes of angle brackets you can use depending on your need. For example, the Dunnings 60 x 100 x 35mm M10 Galvanised Angle Bracket allows you to position the timber at varying heights and can easily be anchored with a nut and bolt configuration. There are single hole variants along with double hole mounting styles. I suggest visiting your local store and having a look at what you'll be needing.

If you need further assistance, please let me know.

Eric

[Halima]

Hi Eric,

What kind of approach would you suggest if the clearance were between 60-65mm ? the 70x35 wouldn't suit the job in that case.

[EricL]

Hello @Halima 

The first thing I would do is to double check the available space. If you only have 60mm to 65mm I'm afraid that is not enough space to install a low-level deck. Unless you can find extra space, I suggest thinking about an alternative cover to the area such as concrete and tiles.

If you need further assistance, please let us know.

Eric