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Back 40 Landscaping

Education Center

Best Practices For Retaining Walls

August 25, 2021

When thinking about adding a retaining wall to your outdoor space, it can get overwhelming trying to figure out if you are going to build the wall yourself or hire a company, what material you should use, and how much to budget for. While you are in charge of your project, and have the last say, there are a number of things that MUST be done, so that your retaining wall not only looks great, but lasts.

 

So, what are the best practices for retaining walls?

 

 Best material to build a retaining wall

If you are looking for a wall that is the focal point of your landscaping, will last a lifetime, and is backed by engineers, then an Allan Block concrete wall in our opinion is a great option for your project.  While some homeowners like the look of wood, a wall that is built with pressure treated lumber will not last. Wood has a life expectancy of 10 years, while concrete is a lifetime product. Resale value concrete is better. Peace of mind. Wood is slightly cheaper.

This is because pressure treated lumber is not rated for ground contact, meaning it is meant to stay off of the ground, never touching soil. This is obviously impossible to do when building a retaining wall out of wood, making Allan Block the best material to use for a retaining wall.

EXP BEL2014 RES Walls Flagstack 001

Hardscape projects located in British Columbia, Canada with products manufactured by Expocrete an OldCastle Company.

 

Building a retaining wall

When it comes to building a retaining wall, the structure and the look of the wall should be homeowner’s main concern. It might be tempting to want your wall built quick, and as cheap as possible, but cutting corners and not using the proper amount of material will only cause headaches for homeowners in the long run.

When excavating the soil where the wall is going to go, it can be hard not to cheat how much soil is getting excavated. The more soil that is excavated, the more gravel that is going to have to be put in its place, and the higher the cost of disposing the soil. The problem with this is that if you cheat the excavation, and do not add enough gravel, your wall will fail. Gravel is essential to the base of the wall to provide a solid level of foundation to build the wall on, and will allow water to drain through the gravel. When there is no standing water, there will be no pressure put against the wall, and no frost heave in the winter time.

Other things that aid to the strength of a retaining wall is burying the first row of brick so that the wall doesn’t slip out, and core filling the back, front, and middle of the wall with gravel.  Typically, contractors do not put enough gravel behind the wall because more gravel is used, and the cost of labor and material goes up.

To get a retaining wall to look straight, and not have any waves in it, is actually a lot harder to do than it appears to be. If you look at retaining walls in your neighbourhood, you will probably see walls that are not completely straight. To get a wall that is straight takes quite a bit of time and skill. This is done by string lining the brick, laying each brick one at a time, and making sure that the brick is level from side to side, and front to back. This process ensures that your wall will be in a straight line.

Cornerstone retaining wall back yard 1

Designing a retaining wall

You might think that designing your wall is as easy as figuring out where the wall is going to go, and what it is going to look like, but there are many things that need to be taken into consideration before your wall is built. Building permits are required for retaining walls that are above 4’, and you may need an engineer to do the wall design in order to get a building permit. When determining the height of the wall, a detailed understanding of site elevations and grade changes are needed to determine how high the wall should be. Remember, a basic retaining wall that is four feet tall and fifteen feet long has to support up to 20 tons of soil pressure. With every additional foot of height, the pressure of the soil increases substantially. This is why it is important to know what you are in for ahead of the build, so you can make sure that your wall is structurally sound, and will last.

 

Hiring an expert to build your retaining wall

When it comes to DIY projects, there are a lot of things that homeowners can do to enhance their property without hiring it out. A retaining wall should not be one of them. Retaining walls are built to retain the soil behind them. Building a structurally sound wall requires heavy equipment, a trailer to get materials in and out of the build site, proper planning, and knowledge on how to build the wall. If a wall fails, the soil that was being retained will collapse, and could cause catastrophic failure. On top of this, the wall will need to be replaced, causing even more of a headache. These are all things that are better left to a professional who can get the job done right, and allow the homeowner peace of mind.

 

At the end of your project, you want to be able to trust that your wall is built properly, and looks great.  Avoiding doing any of these best practices for retaining walls may be cheaper upfront, but will cost more in the long run when the wall has to get redone.

 

Learn about “The ten problems with retaining walls you can’t afford not to know.

 

 

 

 

 

Commerical & residential hardscape landscaping, excavation, drainage and lawn renovation services. Service areas include Abbotsford, BC and throughout the Fraser Valley.

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Abbotsford, BC
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