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Like many Altoona residences, this property front entrance had a series of steps and retaining walls leading up to the front door. Unfortunately, poor construction technique and improper installation of this wall caused it to fail. The force of freeze an thaw on this retaining wall each winter slowly was pushing this wall over.
There are many steps to proper installation of a retaining wall. Improper procedure or execution of any of these steps may to lead to failure down the road. There are many wrong ways to build a retaining wall, but only one right way. Although there are many ways a retaining wall can fail, most walls fail for a few common reasons.
1. Improper compaction of the soil and base of the wall. Proper compaction of the subgrade and base of a wall is very difficult to see, especially once a wall is installed. It is difficult for even an experienced hardscaper to look at newly constructed wall and determine if proper compaction was used in building. However, the longer a wall stands, (or doesn't stand) the more obvious it is if proper compaction equipment and techniques were used.
2. Poor drainage. With every type of precipitation, water collects behind a retaining wall. If this hydraulic pressure cannot be relieved, the retaining wall turns into a water dam. Even large commercial walls with very heavy blocks are no match to the incredible water pressure that can build up behind them. This effect can be heightened by heavy clay-type soils that hold water in them. A wall with proper sized block and effective base compaction is still not effective if there is not proper drainage behind the wall.
3. Backfilling and soil stabilization. Part of the solution to water crises is solved with correct backfilling. If a wall is backfilled with soil, this will trap moisture behind the wall and enhance water problems. Depending on the height of a wall, the soil type and the block used, soil stabilization methods may be needed as well.
While our crew rebuilt this wall, we captured some of the integral parts of proper wall construction. Different types and sizes of blocks, how tall or how long a wall is, and special requirements of load or capacity may cause additional building requirements, which won't be discussed here. The steps of retaining wall construction demonstrated here are universal to all retaining walls.
Compaction of the subgrade below the base of a wall, and compaction of the wall base itself is fundamental to retaining wall construction. Without wordy complex answers, it is difficult to demonstrate proper compaction.
One easy way to understand proper compaction it to look at the machines or tools used. A vibratory plate like the one pictured here is adequate for most residential wall construction. Using a smaller plate compactor can be done, although gaining proper compaction will be more difficult. Using hand tamps or any manual compactors is rarely effective. Improper compaction will lead to many different problems, but ultimately it will always lead to wall failure.
If you hire a crew to build a wall, ask them about the compaction equipment they ae using. Once a wall is built, nothing can be done to remedy improper compaction other than rebuilding. Make sure proper compaction is achieved first.
The base course is the very bottom row of block installed on a retaining wall. How, and where this base course is installed is vital to the longevity of a retaining wall. The entire first course of block must be buried underground. As you can see in the picture above, when dirt work and grading is completed around this wall, the entire first course of block will be hidden. This is also fundamental to wall construction. The buried first course becomes the anchor which prevents the entire wall from sliding forward over time. No matter how tall or short a wall is, or what size blocks are used, the entire bottom course must be buried. On large walls holding a large amount of weight, more than one entire course is buried.
When installing the base course, it is vital that these blocks are installed straight and level. String lines (as pictured) can be used to ensure the blocks are installed in a straight line. A laser and levels should be used to ensure that the base course is installed level.
Water pressure has destroyed many retaining walls. Proper compaction and base course installation are no match for the terrific pressure water behind a retaining wall can create. To ensure proper drainage, water must be dealt with in two ways.
Surface water, or runoff consequent from every rain, must be diverted away from a wall. Whether this is accomplished through swales or catch basins, the goal is that no surface water flows over the top of the retaining wall.
Ground water constantly is moving through the soil stratus behind a wall. To address this, a retaining wall should always be backfilled with clean stone. This allows any water to quickly drain down away from the face of the wall. At the bottom of a retaining wall, a perforated pipe must be installed that allows water to escape at the bottom of the wall. This can be accomplished by extending the pipe out past the end of the wall, or by daylighting it through the retaining wall. Either way, it is important that an escape is created to relieve water pressure behind a retaining wall.
Geogrid is one integral part of this wall that may not be required for all retaining walls. For many walls Geogrid is a necessary step to giving structural strength. This woven, biaxle geogrid stabilizes the clean stone behind the retaining wall. proper installation of geogrid is necessary. When to use geogrid, and how much is required for the project, will vary based on the size of the wall and the blocks used.
When completed, this wall provides an aesthetic solution that will last for decades. Like all Tussey Landscaping's hardscapes, this retaining wall is completed with a lifetime warranty. With all proper construction steps in place, this wall should stand after the workers who built it are gone.
If you want to learn more about Tussey's lifetime warranty walls and patios, contact us today.
6/11/2021 07:07:21 am
I appreciated it when you shared that it is great to reconstruct your retaining wall if it has a poor drainage system. My uncle just mentioned the other day that he is planning to rebuild the retaining wall in his backyard since it keeps collecting water. I will suggest to him hiring a reliable service that can excavate it so he can rebuild a proper one.
6/14/2021 10:41:22 am
I want to get a retaining wall put into my back yard, but I'm not sure how to go about it. It makes sense that I would want to get a professional to help me out with this! they would be able to make sure that the proper soil compaction is done before putting it in so that the retaining wall can last longer.
7/26/2021 09:10:20 am
I want to get a nice retaining wall installed in my back yard, but I'm not sure how to go about it. It makes sense that I would want to get a professional to help me out with this. That seems like a good way to ensure that I handle things properly.
7/26/2021 09:19:40 am
I never realized how essential compacting the wall and its base are to building a retaining wall. I always like to know how something should be made before hiring someone to do it. That way I can have an idea of what is happening and I can call out anything that looks out of place.
7/26/2021 09:23:04 am
I want to get a nice retaining wall made, but I'm not sure what to do for it. It makes sense that I would want to get a professional to help me out with this. They would be able to ensure that the proper steps are taken to ensure that it gets put together properly.
Thanks for pointing out that it will depend on the height of the wall, the soil type, and the block used to ensure the stabilization of the structure. I guess I would let the professionals handle this because I really want a retaining wall built to protect our property since we are near a slope. Hopefully, we have the right fill dirt material since there are area where it needs to be filled to push through with the retaining wall.
9/2/2021 07:16:08 pm
Thanks for pointing out that we should look for professionals when putting a retaining wall on our property to avoid an improper method that may lead to poor drainage. I guess I should look for experts on Monday who can install retaining walls in my backyard within two days. I am hoping to ensure the safety of my five children who love to play outdoors.
9/3/2021 06:42:09 am
I am grateful that this post shared that when looking to have retaining walls installed, it is important that we consider the materials. It makes sense for us to be mindful of the material as it will impact the stability and efficiency of the walls. I will speak with a contractor to ensure that the walls are installed properly.
9/11/2021 01:41:44 am
Having a retaining wall fall apart is not fun at all. You practically have to redo the entire thing, but things like this make it easier. I'm glad we have the internet, thank goodness.
10/1/2021 08:40:45 am
Thank you for outlining the two different ways we can ensure correct drainage when building a retaining wall. My sister is having a retaining wall installed in her yard and I will be sure to share this information with her. I think it would be smart to hire a professional to ensure that the wall is both safe and functional.
10/18/2021 06:23:47 am
Some well-known firms can only fix these issues, and Alex plus is one of them. However, a lot of individuals have appreciated them. Therefore, it is highly recommended to give it a go.
1/25/2022 10:22:55 am
So I just put dirt behind the wall. Water soaks into dirt, and eventually the water's going to make that retaining wall fail. Thank you, amazing post!
1/26/2022 12:00:52 am
I'm glad that you talked about the importance of being aware of minor damages that may affect your property. My brother told me that he is planning to replace their current retaining walls because it is causing soil erosion and asked if I have any idea what is the best option to do. Thanks to this informative article, I'll be sure to tell him that consulting a well-known retaining wall service can answer all his inquiries.
1/28/2022 11:48:39 am
Even large commercial walls with very heavy blocks are no match to the incredible water pressure that can build up behind them. Thank you for sharing your great post!
3/24/2022 09:04:04 am
Landscaping can increase the value of your home.
5/4/2022 06:22:57 pm
As you can see in the picture above, when dirt work and grading is completed around this wall, the entire first course of block will be hidden. This is also fundamental to wall construction. I’m so thankful for your helpful post!
4/6/2023 02:42:40 pm
It was informative when you talked about how rain needs to be diverted away from retaining walls. It seems like it could be a good idea to simulate the flow of water down a slope before you install a retaining wall. I would think that an expert contractor would be able to provide the simulation and and help you pick the perfect location for a retaining wall.
4/24/2023 03:29:35 am
I agreed when you stated that improper compaction may result in many different problems. My friend wants to secure their house with retaining walls. I should advise him to hire a contractor with years of experience in retaining wall installation.
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