Thread: repair brick retaining wall

Originally Posted by jmj

Our 800mm high garden wall has a huge zigzag crack in it It is standing out proud from the other bricks by about 10mm.
Probably a combo of ornamental grape roots and too much water.
Is there any way of shoring this up and perhaps rendering or putting those horizontal stone panels over the top. We don't want to spend too much as we will be moving next year but we do want to make it safe.
Any advice gratefully received

We have a similar problem. Our garden retaining wall has developed a major crack and has began to lean to one side. As you say it looks dangerous but I'm still comtemplating a simple fix. The advice I have been given has left me with 2 options. Remove everything being retained by the wall and rebuild the wall correctly(seems like a lot of work). OR build a new wall in front of the existing wall to solve the problem. You obviously lose space with the second option but it seems a lot easier.
Hopefully someone else out there has another suggestion.

quick fixes generally don't last long, as they won't fix the problem. I would say that the wall doesn't have adequate drainage behind it and that over time the weight and pressure has cracked the wall. It could also be from tree roots, or a lack of strength in the wall itself. The mortar could be weathered and weak, maybe there is no reinforcement. Is the brick double skin (2 bricks thick)?

You could either dig behind it and find the root of the problem, then render over it or put a facade over it, or do what lucky suggested and put one on front. Or, rebuild the damage section, but you would see new mortar marks.

If you try and render over or clad a cracked retaining wall you can pretty much guarantee the cracks will be back within weeks. If you have the space, one option is to build a 500mm high garden bed wall in front of the 800mm retaining wall. This will act as extra shoring and the plants will help hide the cracks on the original wall.

I was involved in repairing a leaning 1800mm high boundary wall that acted as a retainer for the first 500mm or so a few years back. The repairs were designed by an engineer and involved building concrete core filled brick peirs every 2 metres. The footings under these piers where substantial to say the least (600 x 600mm from memory). Even with all this I would have not guaranteed it.

Thankyou very much for your advice. As you suggest, the main concern is getting the footings of the new wall correct.
I had thought of building a wall of the same height about 500mm out from the existing wall and filling it with soil and a garden. It might be stronger to build it closer as you say. .
I guess the only way to do it is to leave the broken wall as is and design a new wall - preferably double brick - the complete length of the wall with fairly substantial footings with some drainage material to help with any seepage. Unfortunately here in Canberra it's difficult getting anyone to do a small job. I guess my hubby and I will just have to get stuck in and do it ourselves. It may not look too good but we will make sure it doesn't fall down and hurt anyone.
Thanks again,
JMJ

Hi,
You are right on all counts. The wall is 30 years old, single skin, there is a massive grape vine which we need for shade as the house faces west and we have been watering it heavily since we moved in 8 years ago to encourage growth. Wish we hadn't!!
I thought of hammering? in some star pickets -we have a few left from another job - about every 30 cm and fairly deeply perhaps using a hole digger. Then heavily plastering and rendering the lot. Then growing some weeping plants along the wall.
Actually in retrospect I think that would look pretty awful.
Thankyou for advice
JMJ

I'de say that's why it's breaking down...single skin brick, no adequate drainage, the mortar would be losing all it's strength. From memory (going back to TAFE days now!) mortar has a life where it gets stronger to 25-30 years, then tapers off again.