How to use blueboard for rendered retaining wall?

[lyndal1]

I have a substantial amount of retaining to do and I would like to achieve a rendered look to suit my home. I am looking to plant the top of the retaining walls. 

I was thinking of treated timber posts fixed framing for the seat part, fixing blue board back filling with Rock against the back to help with water filtering through and running drainage at the bottom. Then I'd render the blue board for a nice finish.

I'm open to suggestions or ideas and please let me know if I'm completely missed something. I have no retaining wall experience. Photo attached of the look I'm after but without the camping tile 

[MitchellMc]

Hi @lyndal1. 

I suggest first building your retaining wall/garden bed as a standalone structure. You'll find this step-by-step guide useful: How to build a raised garden bed. Remember to check regulations in your area, as if the structure is retaining soil, then once it hits a certain height, it will need engineering. 

After you've built your retaining wall from sleepers and posts, you can attach a batten frame of H3-treated timber onto its faces and fix your blueboard to the frame.

Framing isn't enough to retain soil/rock on its own and is typically H3-treated, which means it shouldn't contact the soil. You'll need the H4-treated sleepers for retaining purposes. The reason for the framing over the sleepers, which the blueboard attaches to, is that if you fix it directly to the sleepers, you'll get moisture transferring through them and discolouring your render. It will be best to have an air gap between the blueboard and sleepers, and you might also like to look at sealing the rear side of the sheets when attaching them.

I've created the rendering below to help illustrate.

Please let me know if you have any questions.

Mitchell

 

[lyndal1]

This is fantastic! Thank you so much for the thorough reply. I'll check re the engineering and come up with a plan 

[MitchellMc]

Keep us updated @lyndal1, as I can't wait to see you get started!

Mitchell

[Jason]

Hi @lyndal1,

Great to see you receiving expert advice from @MitchellMc. I'm looking forward to seeing this project progress - I'm sure it will really inspire the community. Please share regular updates.

It reminds me a little of what @Adam_W did in the video below, which you might also find helpful. 

Jason

[suttanto]

Hi

just wondering which part need to be sealed?

thanks

[JacobZ]

Hi @suttanto,

Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you join us.

In this particular circumstance, @MitchellMc is recommending they seal the back side of the blue board as they are creating a cavity behind it where moisture can build up which can compromise the integrity of the rendered face.

Is there a specific project you had in mind? I'd be happy to offer specific advice if you have some details.

Let me know if you have any further questions.

Jacob

[suttanto]

I’m thinking to do similar project

Installing blue board on top of timber sleeper retaining wall

so about the sealing at the back of blueboard

which sealer do you recommend?

thanks

[JacobZ]

Hi @suttanto,

I'd suggest painting Crommelin 1L Exterior Grade Brushable Waterproofer on the back side of the sheets prior to installation. This will create a waterproof barrier preventing moisture build up inside the fibre cement sheets.

Let me know if you have any further questions.

Jacob

[suttanto]

Hi

shall we seal the timber sleeper as well or not

thanks