How to build outdoor seating on cement retaining wall?

[DiFerguson]

Hi, I am keen to have a go at building some wooden seating to sit atop my cement sleeper retaining walls.

I have envisioned a decking look that has an overhang. I am thinking of creating frames for each 2m section, that sits inside the first level of wall and attaching boards parallel to long edge. I would like the bench to overhang the cement sleeper.

I have never done this before but I want to give it a go.  I have carefully pulled apart a pallet, removed all the nails and sorted ‘good’ from ‘bad’ to use for a trial run IF that is a good idea.  

Challenges: 1) The H bracket joins where the sleepers sit. 2) The big chunks of cement left behind by the landscaping (I think I will take a sledgehammer to these). 3) How do I create the nice overhang? (

4) Leveling each section so the frames sit square (I have crusher dust and a manual whacker packer. I also have a drop saw

 

 

 

 

 

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I include photos of my site. The pallet wood I have for test runs and two Pintrest pics that are close to what I am thinking.

Thanks in advance, brains trust.

[MitchellMc]

Welcome to the Bunnings Workshop community @DiFerguson. It's sensational to have you join us, and many thanks for your question about building a bench.

I'd be inclined to make the frame in one long length for the entire seated area out of H3-treated pine. I'd suggest connecting H4-treated posts at the rear that will be concreted into the ground. These will stabilise your bench and act as a cantilever for the weight of seated individuals on the overhanging lip.

I've created some rendering below to help illustrate.

Please let me know if you have any questions.

Mitchell
 

[DiFerguson]

Thanks Mitchell.  I don't have a lot of depth to play with unless I dig out the road base etc. at intervals to sink the posts but that is not impossible and may be more stable and easier in the long run than having the box frame behind the cement sleeper. It would also solve the issue with the H frames (or whatever they are called).

Thank you for your advice.

Di

[MitchellMc]

Hi @DiFerguson,

Looking back at my rendering, I think I've overextended the length of the posts and the depth of their footers. The footers only really need to be in the top of the soil/road base, not sunk right down to the bottom of the wall.

Mitchell

[DiFerguson]

Hi Mitchell,

I thought I would show you the end result of my project after following your advice.

These photos were taken just before I finished the last bench section and before the Merbau tannins stained the retaining wall (I will wait until it stops before I scrub the walls. They are protected from further staining now).

Thanks for your advice, it worked really well and I am really pleased with how it turned out. I am proud of how my first project turned out. 

We will put plants at each end of the two sets of three benches, then do some landscaping and I will start on my deck! Thanks again.

 

 

[EricL]

Hi @DiFerguson 

Thank you so much for sharing that update. You've done very well, that garden seat looks fantastic! I'm sure @MitchellMc will be pleased to see it installed and fully assembled.

Eric

[Jason]

Great work @DiFerguson. I would encourage you to hit the Share a project button and share as many details as you can about the project with the community. I'm sure there will be lots of members inspired by what you have achieved.

Well done,

Jason

[DiFerguson]

Thanks Jason. I will definitely share once I have the plants in and the tannins stop leaching out of the wood and staining the concrete sleepers!

It is going to be a nightmare getting those out! I have already searched this community for advice on how to get the stains out and have tried one product with a wire brush and elbow grease, to no avail. Sigh!

[JacobZ]

Hi @DiFerguson,

It will be great to see everything once the plants are in.

In relation to the tannins, what have you tried so far?

I note my colleague @EricL has shared some advice in the discussion How to remove stains from concrete that might help.

Let us know if you'd like some further assistance, we'd be more than happy to help.

Jacob

[DiFerguson]

I have tried Gerni Concrete & Stone cleaner at 100ml/5ltr water and a steel scrubbing brush.

it has made the concrete purple-ish in patches and sort of helped but not noticeably for the effort involved.