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How to replace a wooden retaining wall?

Hi,

1st time on Bunnings workshop.
Looking for advice….
Looking at removing old rotten wooden retaining wall, and to replace it with concrete sleepers, over 24 metres long.
I was thinking of keeping the existing posts. Only thing is they all vary, from each other, some are 2,400mm to 1,600.
Do I cut off the existing post and drill new holes for the posts at 2 metres apart, so a 2 metre sleeper can slide straight in?
Considering this is over 24 metres, do I do this section by section?

Happy to listen to all ideas/thoughts

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Comments

Akanksha

Welcome to the Bunnings Workshop community, @sthornber. Great to see you make your first post. Trust you've been finding the site a useful resource containing handy advice and inspiring ideas for your home improvement and garden projects.

Thanks for your question on replacing your wooden retaining wall. Our resident Bunnings D.I.Y. expert @EricL will be online later today and will be happy to assist you.

Let me tag @julzdiy, @Baggs, @Dave-1, @TedBear and @Jimi for their thoughts in the meantime.

Akanksha

TedBear

Hi @sthornber, in my experience, trying to work the old in with the new is usually more trouble than it's worth. I suggest that you do remove the old posts as they will likely be a source of frustration and get in the way. I'd be placing the new ones, one at a time as you go, so that any small errors in placement don't become large errors toward the end, especially with such a long length. It would be extra work to have to relocate supports after they are already in place.

[Professional installers might do them all first, but their experience would inform them of how much allowance to make for differences in sleeper length.]

Dave-1

Good morning @sthornber

Id like to say welcome to the crowd 🙂 The Bunnings workshop community is a pretty interesting place to take a stroll through. There will always be one of us that has had a similar issue or can offer some helping words. Downfall of wandering through and looking at the projects is you will get sidetracked! 🙂

I agree with @TedBear for sure in not reusing the old posts (wall) in this instance (I am a big believer in reuse however) You mention concrete sleepers, I am pretty sure they are use dwith Galvinised posts that you slot them into? Could you tell us what type you are considering?

Id mark out the whole retaining wall in the location you want while factoring in garden bed width, whats behind the existing wall, drainage.Id mark it out using a stringline. Then I would go along and put it in stages as 24m will take some time (well for me it would 🙂 )

I have watched a neighbour down the street from my place put this style of retaining wall in and he took at least 6 months without an issue.

The only concern I have is when you remove the old wall either in sections or wholly how far down to those fence support posts go?

Dave

sthornber

https://www.workshop.bunnings.com.au/discussion/comment/32093#Comment_32093

Thank you all for your feedback. A few more images to look at. It looks like it will be a big job for me but willing to give it a go. The cement sleepers will be 2,000 length x 200 height x 80 width

With the fence posts supports, I’m not sure how down they run. Will only know that when I start the job. It’s good point though.

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/78460#Comment_78460

Evening @sthornber

😲 You must be superman! lol Man those sleepers will be on the heavy side! Now that I can see the fence posts you have me thinking of replacing the actual timber rails with tiimber, They are U chanels so could stay in situ and you cut the new timber to length? Unless you are set on the concrete style. Whichever way I would also suggest to put in drainage at the bottom of the retianing wall, It will help prolong the new wall.

Would love to see a pic of the project as it unfolds btw.

Dave

sthornber

https://www.workshop.bunnings.com.au/discussion/comment/103420#Comment_103420

Evening Dave-1

No superman here 😄. I may have a friend to lift the concrete sleepers into position.
I’m thinking of doing this, section by section and removing the old posts and installing new ones 2 metres apart.
My next question, what is the best tool to dig/drill 800mm in depth and what diameter?

Considering I don’t have much room for machinery down the side of the house
Thank you

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/118745#Comment_118745

Good morning @sthornber

🙂 You and your mate may feel like superman after that workout!

Post holes, especially if you are going to be doing section by section I would use a square mouthed shovel cyclone square mouth post hole shovel

Make a square the width of the blade using the blade and work your way down. All my posts that I have put in I used this process. My posts are usually around the 650mm mark and that shovel rocks 🙂 I Actually came across a picture of my shovel (from building my deck) from a decade ago and its still rocking today 🙂

You can hire a mechanical post digger but if you are going to do section by section that may cost a bit. (Never used one before)

Always keep in mind that something may be where you want to dig, waterpipe (Oh yeah I have hit a few lol) sewage pipe (yep did that once when I was a pre-apprentice) or stormwater, let alone power/internet/phone.

Dave

EricL

https://www.workshop.bunnings.com.au/discussion/comment/118745#Comment_118745

Hello @sthornber

It's great that you've received excellent advice from our members. It's a challenging undertaking, but if you do it one section at a time, you'll be able to approximate how long the project will take. Looking at the pictures you posted it seems that the brick flooring was placed after the retaining wall.

It will be necessary to factor in the disassembly of the brick floor to your jobs list. My best advice is to call either your local council or Before You Dig to make sure there are no local services running under the new spot where you'll be putting your posts in.

Please keep us updated with your progress, we look forward to the start of your retaining wall project.

Eric

sthornber

https://www.workshop.bunnings.com.au/discussion/comment/127863#Comment_127863

Thank you all for your input. I certainly have a lot to think about. This information has been very helpful and I feel I have enough to go to giving this job a go

nadula

https://www.workshop.bunnings.com.au/discussion/comment/133806#Comment_133806

Is that discolouration of the bricks on the floor due to water piling up after rain and do you suspect they come through the retaining wall from the high ground? Then I would look at using a agi pipe through the retaining wall or on the ground under the bricks to direct the water to storm water pipe.

Done similar job laying agi pipe through the retaining wall but still too much water piling up next to it, end up using another agi pipe under the bricks.

My two cents as a beginner DIYer 😊

EricL

https://www.workshop.bunnings.com.au/discussion/comment/137574#Comment_137574

Hello @nadula

Thank you very much for sharing your idea. Let me tag @sthornber to make them aware of your suggestion. I totally agree with your idea of putting in drainage at the bottom of the retaining wall. This will divert any water from flowing into the retaining wall panels and damaging them.

Eric

sthornber

https://www.workshop.bunnings.com.au/discussion/comment/137574#Comment_137574

Hi Nadula

The discoloured bricks are from rain, cold damp winter. Rain water has never been a problem around this area. It’s me neglecting the area until now.

There is an existing storm water pipe through the retaining wall. Hopefully that will work

Thank you for your input

sthornber

Hi everybody.
Just an update on the retaining wall. Almost done. Just looking for thoughts and feelings. All materials were bought from Bunnings with a few sausages 😋

I decided to go with wood in the end.
There is a pipe at the bottom, which runs all the way through.

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/34103#Comment_34103

That looks sensational @sthornber!

Well done. I trust you are super impressed with those results.

Many thanks for your update.

Mitchell

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/34103#Comment_34103

Afternoon @sthornber

That looks so good! Nice work and worth the effort 🙂 When you can say "Looks like a bought one" you know its in that good class 🙂

Cant wait for the rain and I bet you will be out there smiling at it!

Thoughts and feels... Envious of a nice job and maybe some little ground clover to go between the fence and timber? 🙂

Congratulations on replacing an old retaining wall!

Dave

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