Rock retaining walls are commonly used in gardens and yards for aesthetic purposes, though some types of rock retaining walls are strong and can be used for heavier duty purposes. Natural rock retaining walls most often use rocks found on or near the property on which the wall will be built — though stones from other locations can also be used — while artificial rock walls are made from prefabricated stones that are cut to about the same dimensions to form a uniform-looking structure, or from other materials cast to look like rock. A natural rock retaining wall can be an attractive addition to a yard or garden, but it is not always the most sturdy structure because of the irregular shape of the stones used to construct it.
Pre-cut stones can be purchased from a landscaping company and will come cut in about the same dimensions. This means a builder can build a uniform wall that is both strong and attractive. Different wall designs are meant for different purposes; load-bearing rock retaining walls will need to be built according to a specific process that will prevent the wall from caving under the weight of the earth it supports. Drainage will be an issue as well, and the builder will have to take steps to ensure water does not build up behind the wall, increasing the likelihood of a wall failure. Rock walls that are meant to support weight are usually built on an angle to allow some soil creep and increase strength.
Decorative rock retaining walls are often built to accent a garden or yard, and while they, too, can be quite strong, natural rocks are irregularly shaped and therefore somewhat unreliable as far as strength and stability goes. A natural rock wall will be built from larger stones and filled in with smaller ones to prop the larger stones into place. Soil can be used to fill in the remaining gaps. In gardens, plants often grow into the wall, which can increase the strength of the wall by providing yet another substance that helps hold the wall together. Plant growth can also damage the wall, however, further making this type of wall an attractive but unreliable one.
A stronger alternative to natural rock retaining walls is a concrete-filled natural rock wall. A concrete wall is essentially built to provide strength and rigidity, but natural stones can be added to the cast to enhance the aesthetic of the finished wall. The stones within the concrete can also add to the structural integrity.