How to build low-level deck on concrete for porch?

[cristianc]

Dear Bunnings Workshop,

First, thank you for making available this resouce, it's great to see so many DIYs succesfully completed!!!

I was planning to build a composite deck over concrete for my porch, but after reading on this forun a post about minimum clearance for decks in Victoria I wonder whether this is actually possible, considering the distance from the concrete floor to the top of the boards would be 130mm, which I was thinking of archiving like this:

Board: 23mm

Slat: 90x45mm

Packers: 15+2mm

Total: 130mm

I'd use angle brakets with concrete bolts to attach the stals and Ekodeck design for the boards.

But please feel free to suggest a different approach or design.

Thank you.

Front viewEntranceSide viewPorch's dimmensions

[JacobZ]

Hi @cristianc,

Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.

Ideally, decks should have clearance allowing airflow to dry out any trapped moisture. Unfortunately, this is not always possible when building over existing structures. In new construction where ground clearing is possible, the recommended 400mm of clearance should be followed, but in your case, you should simply be aware that moisture that gets trapped beneath your deck can reduce its lifetime compared to one with more clearance.

With this in mind, I've created a quick render for you that you could use to construct a deck in this area.

 

This design is essentially two frames that are connected with 4 x 160mm blocks. You'll need at least 10 vertical supports on the frame further from the door and at least 6 on the frame closest to the door.

You can sit the bearers on packers and attach them to the concrete using Dunnings 60 x 60 x 35mm M10 Galvanised Angle Brackets with M10 x 60mm Galvanised Cup Head Bolts through the timber and Ramset 10 x 50mm Galvanised DynaBolts into the concrete.

You can check out How To Build A Deck for a series of articles with lots of information that will be helpful with building your deck.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

[cristianc]

Hi Jacob,

Thank you very much, I'll definitely use your excellent render to build the deck!!! Just one question about the angle brackets, how many would you recommend I use and how should I distribute them?

Thank you.

[JacobZ]

Hi @cristianc,

No worries at all.

I'd suggest they are used wherever you are using packers to support the deck. This will ensure the bearer is held tight on top of its vertical support.

In my render, you can see the blue cylinders that are spaced at a maximum of 900mm beneath the bearers. These are where I would suggest the packers are placed and your angle brackets are used. There are 10 on the front frame and 6 on the back frame. This spacing is in line with the Hyne Timber Bearer Span Tables.

If you have further questions or thoughts about design tweaks, please let me know. I am more than happy to work with you to ensure you have a great plan we can turn into a reality.

Jacob

[cristianc]

Excellent, thank you. I've clear in mind now how to build the frames and attached them to the slab!!!

I'll move on now to the deck it self. Given the unsual of its shape I'm kind of struggling finding the best way to laid the boards.

Thanks!!!

[MitchellMc]

In your circumstance, it would be best to lay the boards parallel to the front of your home @cristianc. Otherwise, you'll end up with a whole heap of short boards, which won't look particularly aesthetically pleasing.

Mitchell

[cristianc]

Thanks Mitchell and Jacob for your suggestions, much appreciated.

I'll get all the materials required and give it a go, and then report back once it's done, thank you!!!

[JacobZ]

I can't wait to see your results @cristianc.

If you run into any questions along the way, don't hesitate to reach out.

Jacob