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How to attach 70x45 joints to bearers for low level deck?

tal_itha

Hi,

I'm planning a small low level deck for my courtyard, around 6.7m2 all up.

The courtyard is entirely concreted, but the deck will not be under cover.

Due to the low clearance and small size, I plan to use mostly 70x45 joists, attached inline to 90x45 bearers.

However, Bunnings does not sell 70x45 joist hangers.

What is the best way to attach these?
I have come up with a couple of ideas so far:

A - skew/toenail screwing using 85mm batten screws, 2 on one side, 1 on the other
B - use 90x45 joist hangers with 4x5mm packers in base of hanger
C - use 60x50 joist hangers with 1x5mm packer in side of hanger
D - use Carinya 80x60 galvanised reinforcing brackets, 1 on either side

Are any of these absolute no-nos? Are any better than the rest? or are there other ways that I haven't thought of (I want to avoid having to drill into the concrete where possible - it takes me forever)

joist options.jpg

And here is a simple drawing of my planned bearers and joists. There will be seating built in around the edges.

Will likely be using builders pedestal feet as footings.

deck 2023_A.jpg

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Comments

MitchellMc

Hi @tal_itha,

My preference would be to screw through the beares and into the ends of the 70 x 45mm joists instead of skew screwing. With that gauge screw, you'll likely split out the ends of the joist if you skew fix. I recommend using two Buildex 18 - 7 x 150mm Climacoat Star Drive Landscape Screws through the bearer into the end of the joist. You'll need to pre-drill before installing the screws.

Alternatively, you could go with the Pryda Joist Hanger - To Suit 50 x 60mm and as it's only 5mm difference you might not need to use a packer if you squeeze the top together.

Please let me know if you have any questions.

Mitchell

tal_itha

https://www.workshop.bunnings.com.au/discussion/comment/30851#Comment_30851

thanks @MitchellMc!

I had read that skew screwing was stronger than end screwing, but I'm glad that end screwing is still an option, as its definitely easier!

Based on your info, I was thinking I could do a combination of screwing with the buildex screws, and using the joist hangers where I can't access the far side of the bearer (eg: where it is up against the planter etc).

EricL

https://www.workshop.bunnings.com.au/discussion/comment/77895#Comment_77895

Hi @tal_itha

That sounds like a good plan, my only recommendation is to make sure to use the Pryda Timber Connector Nails 35 x 3.15mm on the joist hangers.

If you need further assistance, please let us know.

Eric

tal_itha

https://www.workshop.bunnings.com.au/discussion/comment/103026#Comment_103026

HI @EricL , I was planning to use the Pryda Timber Connector Screw 12G x 35mm - is there a reason you recommend the nails specifically?
(The reason being that I can use power tools with the screws, and not have to rely on my (lacking) upper-body strength with a hammer).

Also, couldI use Buildex 16G x 150mm Galvanised Bugle Head Rapid Drive Batten Screws instead of the landscaping screws? Mostly due to them being significantly cheaper.

EricL

https://www.workshop.bunnings.com.au/discussion/comment/118533#Comment_118533

Hi @tal_itha

I suggested the nails as they are the recommended nails to be used with the joist hangers. Using other nails is not recommended as they are not as strong as the Pryda nails. However, if you are using the Pryda Timber Connector Screw 12G x 35mm that will work just as well.

I would probably stay with @MitchellMc's recommendation of Buildex 18 - 7 x 150mm Climacoat Star Drive Landscape Screws. Not only are they bigger, but they are built to withstand the chemical treatment in the timber. Keep in mind that the only thing holding the joist in place are these screws and it's important that they be as strong as possible.

If you need further assistance, please let me know.

Eric

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