Which stirrups to use for low-level deck?

[rhysk]

Hi there, I am building a low level deck and would like to know what stirrups you would recommend for the subframe supports.

As pictured, the deck will be placed over an existing concrete slab and compacted crusher dust.

The deck details are:

Overall size is 3.4m x 3.7m.

Joists at 450mm running along the 3.7m.

Will be using an aluminium 75x50mm sub frame for the bearers and joists with stirrups at 1550mm along each joist and bearer.

Aiming for an overall height of 150mm - 200mm.

 

[MitchellMc]

Welcome to the Bunnings Workshop community @rhysk. It's a pleasure to have you join us, and many thanks for your question about deck supports.

So you'd need supports between 75 and 125mm if you aim for an overall frame height of 150 and 200mm. Or was that including your decking thickness?

Many suppliers of aluminium framing for decks will also have compatible supports for their system. Were there installation instructions that dictated the type of support required? If there isn't a specified support, you could potentially use a floating system and Builders Edge 70 - 170mm Bigfoot Xl Pedestal Feet. You would need to check with the frame supplier to determine whether these feet would be suitable to use with their product.

Please let me know if you have any questions.

Mitchell

[rhysk]

Hi Mitchell,

thank you for the reply.

My overall deck height including the deck boards will be 150-200mm high.

Unfortunately the frame supplier doesn’t provide supports.

Being that a portion of the supports will be set on and over the compacted crusher dust area, I will need to dig holes and fill with concrete for either plastic supports to be fixed onto or I was thinking I could set aluminium or steel stirrups directly into the concrete.

Could you recommend any stirrups I could set directly into the concrete?

I will be using the plastic supports for over the existing concrete slab.

thanks again in advance 

[MitchellMc · Accepted solution]

The plastic pedestal feet just sit on top of the concrete or compacted crusher dust @rhysk; no need to fix them to concrete as it's a floating system.

I'm unaware of any stirrups designed to carry a 70mm joist. They are designed to suit posts or larger joists, so the vertical flange on top is taller than your 70mm joist. You'd need to cut the vertical flange down so it doesn't impede the decking being laid. If you were prepared to cut the flange down and potentially drill a new hole in it to suit your joist, then something like this Pryda Post Anchor Half Stirrup 300mm M10 could be used.

Mitchell