How to stop neighbour’s garden coming through fence plinth?

[JesseS6]

Hello,

So my fence shared with my neighbour looks like it should have a retaining wall installed, but only has standard plinths. Due to the height difference their garden bed and soil is coming through and broken the plinths. We plan to have a path to a deck, with boxed garden beds along the path
How can I stop this and also fix it aesthetically? 

 

 

 

[MitchellMc]

Hi @JesseS6,

You're absolutely right—a retaining wall is needed here. Plinths are only designed for aesthetic purposes to close gaps under a fence, not to hold back soil. Since the soil from your neighbour’s side is pushing through and has already damaged the plinths, the situation will only worsen over time. Installing a proper retaining wall now would be much easier than waiting for a complete failure, which would make the project far more involved.

As this is a shared fence and the issue is caused by soil from your neighbour’s side, it’s important to have a discussion with them about the best way forward. Retrofitting a retaining wall beneath the fence would be the ideal solution, but this may require excavation on their side. Without their cooperation, you may have to sacrifice part of your own property to build a retaining solution, which isn't ideal given that the problem isn’t due to any fault of your own. It’s best to raise the issue with them sooner rather than later to find a practical and fair resolution. 

Please let me know if you have any questions.

Mitchell

[JesseS6]

Thanks @MitchellMc

Could I Build a raised garden bed using 50mm sleepers at the same height. Using the galvanized sleeper posts concreted in. At the back, only have the top sleeper. and the bottom 1-2 sleepers install these between the fence posts and concrete them in using vertical cut offs. And fill in.

Aiming to support the plinths from further damage with the sleepers concreted in, also not making my neighbours situation worse.

But hidden aesthetically by soil.

Does that make sense?

[MitchellMc]

The plinths are almost destroyed and not long for this world @JesseS6. You could effectively build a raised garden bed directly in front of the fence, which acts as a retaining wall as well. 

I'm not sure if I entirely follow "At the back, only have the top sleeper. and the bottom 1-2 sleepers install these between the fence posts and concrete them in using vertical cut offs. And fill in.".

I'd created the garden bed directly in front of the posts. There will then be a void between the back of the raised garden bed/retaining wall and the plinths. I would simply pop a couple of sleeper behind the bed to take up that gap. The plinths/soil will push on these sleepers, which in turn are held in place by the back of the garden bed.

I've created the rendering below to illustrate.

Mitchell

[JesseS6]

Hi @MitchellMc ,

Just coming back to this as I am now ready to get this built.

If I use the 50mm Retain it steel posts, at 1100mm height for a 600mm (3 sleeper) wall. How long can each length be? can it be the full 2.4m ?

How should the posts be set in the concrete? I am assuming a 300mm wide x 500mm deep hole for the post and using Bastion 20kg Quik Set Concrete. How many bags would be required per hole?

Lastly is there a trick to ensure they are all aligned and posts are straight, I have seen some people put a sleeper in aswell as a support for the post to keep them straight, are there any issues with that approach?

Would this require AGI pipe to be installed behind it also? As it will be as close to the existing fence as possible, i'm thinking to just add loose scoria behind it to fill the void.

[JacobZ]

Hi @JesseS6,

With 50mm thick pine sleepers, at a 2.4m span, there is some potential for bowing if the soil on the back is pushing on it. If you don't plan to remove the plinths, I wouldn't worry too much, but if the soil were allowed to fully press on the back of the sleepers, I would consider adding a midspan post or using hardwood sleepers or 75mm sleepers instead.

Those dimensions look perfect for your concrete. With a hole that size, you would be looking at roughly 3 bags per hole.

The trick to getting them nice and straight is to set up a string line using timber stakes and some builders' line. Get it nice and taut, then start at one end and work your way along the string, pouring concrete in the hole, then pushing your posts down into the concrete so they are just touching the string line. You can attach a Magnetic Torpedo Level to the posts to get them nice and plumb in both directions. Assuming you have dug your post holes based on the length of your sleepers, they should be relatively close to where they need to be. You could drop a sleeper in to act as a gauge, or you could just measure using a tape measure. While the concrete is dry, there will be some room for movement. It is also worthwhile, once the last post is put in place, to go back to the first post you put in and check it to ensure it hasn't shifted.

Due to constraints on space and the fact that the soil won't be actively pushing against the back of the retaining wall, I wouldn't worry too much about agi pipe. Some drainage gravel or scoria should be fine.

Let me know if you have any further questions.

Jacob

[AlanM52]

Hi @JesseS6,

Crikey... for than amount of damage there must be major forces at play on the other side.

Looks like someone has already attempted repair work.

Fencing laws vary from state to state but generally there is a responsibility to ensure the bottom of plinth boards are clear of soil and debris - certainly not the case here.

Jesse we need photos of the other side please.

Is your neighbour the owner of the property?

Cheers