How to build a low-level deck?

[PscottDIY]

Hi Team,

planning on building a deck under our new patio approx. dimensions;

~8200L

~4700W ( can be flexible on this to suit a standard board length to avoid cuts ) 

~150/200H 

ideally wide Boards running out to the grass. 

Most of it can be supported by an existing concrete patio, with I assume some footings on the outer side closest to the lawn.  

Can you please help me with how so set out the frame / bearers / joists  footings etc ? what sizes to use etc ?

Cheers 

[Jason]

Resident Bunnings D.I.Y. experts @MitchellMc and @EricL will be back on the site on Friday @PscottDIY and happy to help.

Thanks for your patience in the meantime.

Jason

[MitchellMc]

Hi @PscottDIY,

I apologise for the delay in my reply. Your plan looks great; well done putting it together. My only advice would be to add at least one or two more bearers into the equation. 90 x 45mm spanning 1591mm is likely within tolerances, but it's getting up to the max span. It begins to flex underfoot at that span, and there's a risk that you'll end up with a bouncy deck. Adding additional bearers reduces that span, and the deck will end up more solid. Generally, I like to have the bearers around the 1000mm mark, so eight bearers will bring you closer to that.

Please let me know if you have any questions.

Mitchell

[PscottDIY]

Gday I have updated the post with my latest plan if you could please have a look, cheers 

[MitchellMc]

That looks spot on now @PscottDIY.

Mitchell

[PscottDIY]

Cheers @MitchellMc @all good with the single 140x45 for bearers ? ( no need to double up ? ). Also my plan of angle brackets and shims to brace the bearers to the concrete - in my head it will be nice and solid with the existing concrete bearing the load ? 🤔

[MitchellMc]

I don't see any need to double-up the bearers @PscottDIY. You'd only do so if they were spanning too far, and they are currently supported at 1121mm, which is fine.

Plenty of our members have successfully used angle brackets to support bearers over concrete. I haven't come across them experiencing any issues with that.

Mitchell

[PscottDIY]

cheers @Mitch , couple of questions;

- how do you recommend to join the joists as the span will be longer than standard lengths ? 

- do you recommend noggins to the joists ? 

- what fixing is good for joists to bearers ?

Thanks 

[EricL]

Hi @PscottDIY 

The three most common methods to join joists together are butt joints with steel plating, lapped or staggered joints and bevel butt joints. These joints are often placed over the bearer.

Anything that helps to reinforce the joists is always a plus. I'm definitely in favour of installing noggins to the joists.

Aside from nailing the joist to the bearer, I suggest having a look at the Pryda Triple Grip Right Hand in combination with Pryda Timber Connector Nails 35 x 3.15mm 500g when anchoring the joist to the bearer.

If you need further assistance, please let us know.

Eric

[PscottDIY]

Cheers @EricL any products recommended for the joist butt joints with steel plating ?

the lapping looks the easiest but then the finish of the screws will be offline.. ?

[MitchellMc]

Hi @PscottDIY,

You can use Pryda Nail-On Connector Plate 75 x 250mm for butt joints. I'd agree that for consistency of screws, I'd go with the butt joint.

Mitchell