Why is my retaining wall failing?

Offering reliable landscaping services to homeowners in British Columbia since 2013

Picture of Natasha Maerz

Natasha Maerz

Owner/Office Manager

You replaced an old failing retaining wall or had a new one built, and now your retaining wall is failing.

Whether your wall is new or you replaced an old wall it is extremely frustrating to have to deal with replacing a “new” wall. Not only does this wall failure mean that you have to go through the stresses of having a wall built again (think a messy yard, a crew coming to your home every day etc.), but you are now spending double (or triple) to have the wall replaced.

Retaining walls are not as easy to build as they look. The top reason why your retaining wall is failing is because whoever built it did not build your wall “properly”. In this article we will get into what a proper wall looks like, and why it is so important to have a trained and certified builder build your retaining wall.

If we haven’t met before allow us to introduce ourselves. We are Back 40 Landscaping and our expertise is in retaining walls and hardscaping. We are certified and trained retaining wall builders. Our entire crew has their Allan Block certificate!

As stated above, retaining walls fail mostly because of the way they are being built. You can have two contractors using the same material, such as Allan Block, and have drastically different results for your wall.

Your Allan Block wall is not built properly

Retaining walls that are not built correctly, will eventually fail. During their lifetime they will start to have minor separation between blocks, and large portions of the wall may fall over.

Walls that are not build exactly to Allan Block specifications fail. Cost saving methods when building the wall is why these walls eventually fail. Cost savings include not using enough gravel behind the retaining wall (some contractors even use soil behind the wall which will push your wall over!), not digging the trench deep enough and removing enough soil, (some contractors hand dig) and not using a laser level to get the base of your wall perfectly straight ( resulting in a wavy wall).

The contractor building your wall is not certified

Allan Block offers certification courses, training, and requires contractors that are a part of their program to submit their wall after build for inspection. When a contractor has the backing of Allan Block and their experts this ensures that your retaining wall is built exactly to Allan Block best practices and will be built with the proper amount of excavation and gravel.

Many contractors out there have taught themselves how to build retaining walls. While this is great, they do not have any accountability to build a proper wall. Walls that are built without enough gravel or soil taken off of the site can be built cheap, after all the material and disposal costs are cut in half or even more than half.

This is truly why homeowners should ask themselves why some contractors walls are priced so low, while others are high. You cannot compare a retaining wall cost apples to apples when your contractor does not have the right education behind them to back them up.


Your retaining wall is backfilled with soil

You might be sick of hearing about what your wall should be backfilled with, and fair enough! This is such an important part of your retaining wall built we have to talk about it again!

Many retaining wall builders want to cut costs where they can. Not only will they save money, but they will get more jobs because their prices seem so appealing to homeowners.

They way that costs can be cut is by limiting the labor and cutting down on materials to build the wall.

Limiting the labor and materials for your retaining wall build looks like this:

  • Not excavating enough soil in the trench (This lessens soil disposal and labor)
  • Not replacing the soil with enough gravel (In some cases the soil from the trench is reused)
  • Laying the base of the wall by eye instead of laser level (Resulting in a wavy wall)
  • Not adding any drainage behind the wall (Heavy soil will push your retaining wall over)
  • No engineering on your wall (This depends on how high your wall is)
  • No geogrid (Again this is just on an engineered wall)
  • No filter fabric is used


So how do you know that your wall is not going to be built to Allan Block specifications?

The price of your wall is a dead give-away if your contractor is trained and going to follow those specifications.

What can you do to protect yourself and ensure that your retaining wall does not fail?

To ensure that your wall is going to be built with standards and will last, do your homework as the homeowner.


  • Look for red flags such as a company that is not certified or trained in building retaining walls.
  • See what equipment a company has (no machines mean hand digging, and a trench cannot be properly dug by hand)
  • If your retaining wall price is too good to be true, it probably is
  • Timeline (Small walls take about a week, while a large two-tiered wall will be roughly a month)
  • The crew (Who is going to be building the wall? how many of the crew are certified in Allan Block retaining walls)
  • See how many walls your contractor has built
  • Check if you contractor has every built a engineered wall with geogrid


A retaining wall built well gives you piece of mind, a durable wall that is going to last you a lifetime, a beautiful focal point, higher resale value of your home, and only needs to be built once.