Retaining walls: The ins and outs

Photo: Redi-Rock

We all have some clients who rely on us for every job in the countryside, while others like to do it themselves and try a few projects on their own.

While there is no harm in setting up on your own to complete a few smaller projects, there are some that desperately need professional help. One project that requires special attention is the installation of a retaining wall.

It can be difficult to convince a handyman that you need to be the one to do a project like a retaining wall. Ultimately, however, it is crucial that you help him understand the dangers that can arise if he tries this project himself.

Retaining walls are used to help landowners negotiate slopes. They often have visual interest and a functional purpose. Retaining walls can be used to increase the amount of usable land in a yard and they can even provide environmental benefits, e.g. B. protecting areas from saturation and reducing soil erosion.

Building specifications

Techniques for steeper slopes include the use of interlocking concrete blocks, wooden retaining walls, riprap areas (loose rock), patios, and rock retaining walls. If you choose to use wood, be sure to treat the wood with a preservative to prevent rot.

If the wall is higher than 3 to 4 feet, zone codes and regulations require an engineer to assist with the project.

The wall should lean into the mound a minimum of 1 inch per 12 inches of height for safe loading of the wall. This can also help with drainage if the soil becomes saturated. There is also the option of redesigning the slope of the slope before installing the wall. This can help draw the water away from the wall and can also reduce the slope required.

Placing drainage tiles behind the wall can help prevent water from pooling in poorly draining floors. Make sure you construct these tiles with a 12 inch deep layer of backfill that drains freely, e.g. B. gravel.

The cost, function and height of the wall will depend on the materials your clients choose for the project. If the wall was to be used solely as a decorative piece in the yard, almost any type of material would do the job. For the walls, which must serve to carry large loads, it is necessary to use durable, long-lasting materials suitable for the conditions of the site.

Wood and solid concrete walls are only recommended if the wall height is less than 4 feet. Wooden walls deteriorate faster and concrete walls have drainage problems that can lead to water-saturated conditions above the wall.

Look what

While respecting your client’s landscape, keep an eye out for areas that may require a retaining wall. Some things to keep in mind are:

  • What’s the slope? If the slope is greater than 3: 1, contact a technician. If the slope is greater than 2: 1, structures or special stabilization techniques are required.
  • How much freeze or frost does the wall and the floor it supports come in contact with?
  • Check the drainage and see how it is. If water appears to be flowing heavily on the floor and wall, drainage may need to be added.
  • What type of floor does your customer have? Soils with a high clay content do not drain well, but they are less prone to erosion. Sandy soil has the opposite properties.
  • Look for other structures near where a retaining wall may be required. If there are existing structures, consider how they will be affected when a retaining wall is installed.
  • Are you and your customers in an earthquake prone area? In this case, you should consult an earthquake engineer to analyze the wall and make it more seismic.

Four types of retaining walls

Once you’ve determined that your client’s yard needs a retaining wall and have discussed the importance of having that wall installed professionally, it’s time to determine what type of wall your client will need.

Gravity walls: These hold the earth through the weight of the wall material. They can be formal paving stones or even a pile of large stones, but they can fall easily and should be used for short slopes of 3 feet or less.

Anchored walls: This is the strongest type and can be combined with other techniques. An anchor is wrapped around the wall and a base is placed deeper in the mound, which provides stabilization.

Pile walls: These use long stacks or poles that go deep into the ground and above. Posts can be made of metal or treated wood and have a good ability to hold back the ground.

Cantilever walls: These are similar to pile walls, but are given additional strength by a kind of “arm” that extends back into the hill. This can increase the ability to stabilize pressure.

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