Gravel board problem

simbrind

Hello, I'm a novice and I was wondering if anyone had any ideas how to solve the following:

Our garden is lower than our neighbours, it is banked at the fence. I need to level my garden but this will mean the existing gravel board isn't deep enough and I imagine will risk next doors garden spilling into ours under the fence over time. 

Is there an easy solution to this without replacing the fence? My initial thought was to add a deeper gravel board by attaching it to the existing one our our side. Thanks in advance for your help.

I have attached a photo with a small section dug out to show the depth that I am working with.

simbrind

Also, the fence posts are wooden and not concrete, so I can't add concrete board

Dovefromabove

I can't see why your solution of adding a lower board will be a problem, and it will give you the opportunity to create a Hedgehog Tunnel 

https://www.hedgehogstreet.org/help-hedgehogs/link-your-garden/
Concrete boards are disastrous for hedgehogs and are hastening their decline 

One point to watch is the fence posts ... how deep are they ... lowering the garden on one side may weaken them.  Don't want the fence to come crashing down!  Our neighbour's garden on one side is higher than ours ... we have a metre wide bank supported by sleepers alongside that fence which we treat as a raised bed.  

On the other side of our garden the neighbours' garden is lower ... our builder built up a wall of concrete blocks to stabilise the bank that side and our fence posts go through the blocks and down into the soil.  

raisingirl

If you put a gravel board or something wider and heavier, like a railway sleeper perhaps, along on your side, you can keep it firmly in place by banging in stout wooden posts in front of it - you'll see steps made this way (e.g. this page 'simple log step' sectionhttps://www.diy.com/ideas-advice/how-to-build-garden-steps/CC_npci_100146.art ) and the principle will work if it's only the depth you've shown there. I wouldn't go much deeper than that and remember the board is buried at the back so to reduce the risk of it rotting, don't bury it on your side (building a raised bed or summat). That way damp coming through the ground behind can dry off the surface on your side. if you paint the back of the boards with 'black jack' or staple some old compost bags to the back, the board will last longer still. But no wooden retaining structure will last forever so do it in a way that allows you to replace them later. Such as put in the stout posts and just slot the board in behind so you can lift them out and drop a new one in if you need to. 

The permanent solution is a very short concrete, or concrete block, or brick 'stub' wall along there (concrete blocks laid on their sides will be very stable).

simbrind

Thanks, the depth where I've shown is approx 8-10 inches, and it goes down to approx 3-4 inches at the other end.