How to build low profile decking?

[Skimmo24]

Hello all,

I would love to get some advice in relation to a DIY ekodeck that in preparing to build in our backyard.

The area which i intent to deck is over concrete with the area being 4490 x 3260.

The decking height (matching the height of the sliding doors) is 80mm including the decking (for which ekodeck is 23mm thick).

My main concerns arise around the building of the subframe, would it be possible/safe in using 45 x 45 in building subframe?

I plan to hold up the subframe with some galvanised L brackets (4mm thick) held into the concrete with 12x75 galvanised dynabolts.

Ive drawn a little diagram with what ive written above. (Sorry im really not well versed in construction lingo).

Any advise will help! Thank you!

 

[MitchellMc]

Welcome to the Bunnings Workshop community @Skimmo24. It's wonderful to have you join us, and many thanks for your question about installing decking.

There are not any 45 x 45mm joist option that I'm aware of and that wouldn't typically be a large enough clibre timber to support your decking. I suspect you'd need to use 90 x 45mm on its side for your extremely low-level deck. Be aware that by creating such a low-level deck that will lack adequate ventilation, your timber will have an advanced rate of decay and its lifespan shortened.

Once you subtract the 23mm thickness of the decking from your 80mm, you'll be left with 57mm. After the 45 mm joist, you'll have a gap under it of 12mm. You might be best using 10mm plastic shims under your joists and then Dynabolting directly through the face of the joists into the concrete.

Here's a helpful guide: How to build a low-level deck.

Please let me know if you have any questions.

Mitchell
 

[Skimmo24]

Thanks so much for the advice! I will be using 90x45 on its side to make the subframe. 

Just further questions arising from the insight given;

1) if dynabolting straight into concrete through the face side and using shims, would I be dynabolting through the shims as well, or placing the shims on either side of the dynabolt?

2) The deck is going to be built fully under cover, would you recommend putting deck protect tape on the top of the subframe?

3) Would you say 90x45 is better for my project than 70x45 (producing much more stability?

Thank you so much in advance!

[EricL]

Hello @Skimmo24 

It's not necessary to drill through the shims as you can place them on either side of the Dynabolt. Any extra protection you can provide for your deck is always a plus. Putting CAgroup 100mm x 20m Bearer Protector G-Tape means that water will not sit on top of your decking frame.

Using the larger timber 90x45 is an advantage as it provides extra strength.

Since you've made preliminary plans on paper, I suggest drawing the decking frame on paper as well to give you an idea of timber quantity and the number of panels you'll be needing for your deck.

If you have any other questions we can help with, please let us know.

Eric