True to their name, retaining walls are built with the intention of holding back huge chunks of compacted soil that would otherwise erode into your landscape. The various types of retaining walls (gravity, cantilevered, anchored) might be confusing for an average homeowner. It's important to understand the various factors that should shape your choice of retaining wall if you intend to get the most out of this 'solid' investment. Below is a discussion on two of these factors.
Soil Type and Drainage
The type of soil you want to hold back and the nature of drainage within the landscape can have a significant impact on your choice of retaining wall. This is because soil will exert pressure on the retaining wall. A wall that's built to last must have the capacity to bear pressure exerted by the soil. Take expansive clay soil as an example. The volume of expansive clay soil increases significantly when the soil absorbs water. When this water is lost, the soil shrinks back to its original volume. Thus, the amount of pressure exerted on a retaining wall will fluctuate depending on the soil's water content. Drainage becomes a significant factor because it will have a huge impact on soil water content within the landscape at any given time. If you were to choose between a retaining wall made of concrete and one made of timber, the concrete wall will probably handle the fluctuating pressure exerted by expansive clay soil better.
The different types of retaining walls have different construction requirements. For example, gravity retaining walls depend on the mass of the wall to hold back soil while the cantilevers on cantilevered walls distribute pressure exerted on them to the ground. For maximum stability, the base of a gravity wall will need to be as thick as possible. The higher the wall, the thicker its base should be. Cantilevered walls will work well with a narrower base thanks to their mode of operation. If you're working with limited space for wall construction, a concrete sleeper wall would be a good choice based on the fact that it's a cantilevered system. If you've got the luxury of space and a high heap of soil that needs to be held back, a concrete crib wall would be a better choice. Have it in mind that poor construction is among the most prominent reasons for the failure of retaining walls. Make sure to ask your landscaping contractor about their experience building retaining walls.