Support for retaining wall with steel posts

[Sharath]

Hi,

I'm building a retaining wall with 7 steel's posts. The posts are 1.8m apart. I'll be using timber sleepers in between. How do I provide support to timber sleepers in the middle? The timber sleeper requires support at 1.2m, I'm over engineering and intend to provide support at 0.9m.

[MitchellMc]

Welcome to the Bunnings Workshop community @Sharath. It's fantastic to have you join us and many thanks for your question.

Congratulations on over-engineering as it's usually the other way around. Can I ask the height of the wall and if it requires engineering? 

The sleepers require support at the midpoint. That support would be another post cemented into the ground and it will need to be on the front side of the wall.

You might be interested in reading through these previous discussions-

• How to build a timber retaining wall? by @Dheeraj

• Retaining wall in progress. by @MandaH

• Leveling backyard by @ximian

Let me mention @Adam_W  and @Yanick to see if they can provide their thoughts. However, I'm sure they'll need to know some more details like what the wall is retaining, the height of it and if it needs to be officially engineered.

If you haven't already, I'd recommend viewing Adam's D.I.Y guide- How to build a retaining wall.

We look forward to hearing more details about your project and providing some great solutions.

Mitchell

[Sharath]

Thanks @MitchellMc , the wall will be 600mm tall above ground level. 

Oh that's great to know there are support posts. I see steel joiner, corner and end posts available to buy. I haven't come across posts which act only as a support, maybe I haven't been looking at the right places.

[MitchellMc]

@Sharath,

I apologise if the information I provided wasn't clear. If you wanted to place a mid-post you would need to use a vertical sleeper concreted into the ground. If you would like to keep the posts minimalistic, as with the Retain-iT system, you would need to cut the 1800mm sleepers at the mid-point and install a joining piece as your post.

These might not apply to you and regulations are sometimes deferred to the local council, but here are some guidelines on height restrictions for non-engineered retaining walls-

• Australian Capital Territory: 40cm

• Queensland: 100cm

• New South Wales: 100cm

• South Australia: 20cm

• Tasmania: 100cm

• Victoria: 100cm

• Western Australia: 50cm

These regulations might benefit others when reading this discussion. If your wall is over the allowable height in your state, please seek an engineers assistance in designing the wall. They will be able to advise on suitable construction techniques.

Mitchell

[Adam_W]

Hi @Sharath one of my favourite projects!
As Mitch has mentioned do check with your local council as there are state and council regulations regarding heights of walls before full engineering is required.
You are right in wanting a support in the centre. Most of the steel supports are designed for sleepers to drop or slot into them so this means a centre support would stand proud from the wall.
You could use heavier sleepers. 50mm is most often used but you could go up to 75mm. Or use shorter lengths, eliminating the need for a centre, bowing would be unlikely with a 75mm sleeper over a 1.2m length.
The other option is to consider concrete sleepers...