How to fix rock retaining wall?

[benchassis]

Hi there, 

I've moved into a new property that had an overgrown garden. I've been periodically removing the overgrown plants, weeds and dead trees but now it appears to be causing the rocks from the retaining wall to fall down. 

There was an old Lantana which had weaved it's way through the rocks along with other invasive vines & weeds which I want to remove, but the more I remove, the more rocks fall out. 

How can I repair the rock face and keep the rocks in the wall whilst ideally continuing to landscape the top of the garden bed?

[JacobZ]

Hi @benchassis,

A warm welcome to the Bunnings Workshop community and thank you for your question about your rock retaining wall.

It looks like the wall was built by stacking stones and possibly using mud to bond them together. It can be an effective technique if done well, but it appears the roots have grown down through the soil, which can help lock things in place, but once removed, it will leave cracks and cavities that will weaken the wall.

When stones fall out of the wall, I'd suggest tidying up the hole that they fell from by carefully brushing away the loose dirt, then applying some mortar to the cavity before pressing the stone back into place. You would essentially be replicating what I assume was done originally with a stronger bonding material.

If while you are continuing the landscape work, you find that the wall begins to degrade considerably, I would consider replacing the wall with something more modern and designed for purpose, such as retaining wall blocks or concrete sleepers, keeping in mind that retaining walls over 1m tall require engineered plans and submissions to council for building approval.

Let me know if you have any further questions.

Jacob