Retaining walls last a lifetime when they are built using the right amount of materials and done by a certified retaining wall builder.
Being in the retaining wall industry for over eight years, with Allan Block training and certification, our goal is to educate homeowners on all things retaining walls and help them make a more informed decision with their project.
Look around any neighbourhood and you will see examples of wall being built by inexperienced contractors or homeowners. Those walls fail eventually.
Why do retaining walls fail?
There are numerous reasons why retaining walls fail! The most common reasons are that not enough soil is getting excavated and hauled away off site, lack of gravel behind the wall, no drainage system, and having an inexperienced person build the wall.
How does price effect how long my retaining wall lasts?
The price effects how long a retaining wall lasts due to how the wall is built, what it is being built with, and who is building it.
Price factor #1 The excavation for the retaining wall
When building a retaining wall, excavating enough soil behind the wall for drainage is one of the most expensive components to the build.
Anyone who is hand digging will no doubt cheat the excavation due to how labor intensive it would be to dig that deep of a trench.
IF someone managed to dig to the correct depth ( which is highly unlikely), they would need to wheelbarrow out all of that soil, and find somewhere for it to go. Soil expands 1.3x its size once excavated, making this a large endeavour.
Another factor that comes in is that disposing of soil is expensive.
To be able to actually get rid of all of the excavated soil you need a track dumper that can haul the soil from the dig site to the road, a machine to load a dump truck, and a dump truck to dispose of that soil.
All of these machines, the cost of soil disposal, and the time to excavate, play into how much your retaining wall costs.
Price factor #2 The gravel put in behind the retaining wall
Retaining walls require a drainage zone of 12-24” behind it. This is a lot of gravel, and again the question becomes, how will all of that gravel get into your yard?
If the amount of gravel placed behind the wall is less than needed the retaining wall will fail.
Some contractors cut costs by putting the soil that was excavated behind the wall.
Using soil behind a retaining wall will lead to the wall collapsing due to the heavy soil being pushed up against the wall, and the fact that there is no drainage behind the wall (water can pass through gravel, not soil).
While using soil instead of gravel makes the cost of the retaining wall significantly less, it lowers the walls life expectancy by years.
Price factor #3 Education
Building a retaining wall takes skill and training. You can watch how to build a retaining wall on YouTube and get the basic information on how to build a wall, but that is where the education stops.
Allan block has three levels of certification for wall builders that teach contractors how to build walls to Allan Block specifications.
To get certificated contractors are required to go through a course, and then take a test.
Every wall that is built after the contractor is certified gets logged with Allan Block and there is ongoing education.
This certification takes time, commitment and is a paid course.
A contractor that does not take the time to educate themselves on best practices, learn from experts, and get ongoing support from professionals, will not be building the same type of retaining walls as the latter.
Price factor #4 Basing the retaining wall
No doubt basing a retaining wall is one of, if not the most, important step of the entire retaining wall build.
The first layer of the wall needs to be perfectly straight.
If it isn’t the rest of the wall will have curves in it, and the integrity of the wall will be compromised.
Basing is a skill that is learned from education, and there are tools that can help get the first row of blocks perfectly straight.
String lines are used as a guide for the wall and allows the contractor to see that each block is placed in the correct place.
Another tool that is used is a laser level.
The laser level ensures that everything is completely accurate, and there is no guessing when it comes to whether the blocks are perfectly level and straight.
It seems easy enough to have a string line and laser level for when a retaining wall is getting built, but most contractors skip this step.
Why do they skip this step? It is labor intensive and takes much longer to set up string lines and laser levels correctly than it is to eye ball where the blocks need to go.
While each block is placed meticulously with the string line, eye balling will cause a wall to be wavy, and uneven.
Laser levels are expensive, and take a bit of work to set up so that they are reading data accurately.
Again, not setting up a laser level will save time, cutting down on wages for the crew working on a retaining wall.
Price Factor #5 Protecting your space
Most construction sites look messy and homeowners’ yards will look worse before looking better! When machines are involved, yards will be torn up by tracks coming in and out hauling materials.
If a homeowner has an established lawn that they want to keep clean and intact, plywood roads can be built so that the machines do not go on surrounding areas.
This appears to be simple, however, plywood roads take quite a while to set up and keep clean, and at the end of the project to be hauled away.
Plywood costs money to buy and time to haul. Due to the size of the plywood, an extra trip to the site will need to be done to deliver it.
Cleanup after every day on the job site is imperative to keeping down on dust, and to ensure that neighbours are happy. No one wants to be leaving their home and driving through a dirty road.
While plywood and cleaning up after each day seems simple, it takes time, planning, labor and materials to do so. Again, this is why most contractors will skip this step.
Clean up and protection of your space may not be something that you need, and costs can be cut here and there, but if you want a retaining wall that will last, and do not want to worry about having to replace it in three years, be prepared to spend more on your wall build.
Upfront it may not seem worth it, but the time, headache and money saved from having to get your wall rebuilt will make you happy you did.