This article will go into detail why concrete walls are a good option for mild climates and modern homes. We see examples all day of poured concrete walls along freeways but seldom appreciate the skill involved. Many things can go wrong in the process so it is not an easy feat to do this on a massive scale like the Department of Transportation. The contractor must be experienced because it's a difficult solution for residential landscape retaining walls. Contractors in areas of weather extremes or heavy rainfall try to avoid fine poured concrete due to its challenges. When a wall fails, you have to build a new wall from scratch. Cracks are also a huge problem because patching them is so difficult that the entire wall can be a loss. In areas with better weather like southern California, there is more interest in this modern design aesthetic. A major factor is the skill of the concrete contractors. The forms have to be on point, otherwise you risk a wave or bulge in the wall
so this can destroy the look of the project. Also, the concrete has to be finished perfectly to get a smooth surface which can be difficult because there is so much steel inside. This makes poured concrete for retaining walls less of an option for residential landscapes.
The resulting changes in processes for more reliable retaining wall systems and the use of a CMU core allows the landscaper to achieve a great look without the cost or risk. However, some landscape architects and their clients who extend poured concrete architectural elements of a modern house must bring this material into their exterior walls and retaining walls.
Landscape architects can use either method but there's no question, an 8" concrete wall is stronger than an 8" block wall. For greater control of moisture intrusion, additional mixtures can be used. For walls under four feet, a Simpson tie system will allow for the walls to be poured quickly with a high degree of success. The downside is that it takes a long time to build the forms, but once they're up and the pour is complete, there's nothing more to do.
The majority of landscapers today can achieve a similar look of poured concrete with a block CMU core plastered. They can use block with a hard trowel plaster that looks identical to poured concrete. Another option is to use smooth stucco that looks just as good.
If poured concrete is to be used, it should be designed by a landscape architect to ensure there is adequate footings and steel. For example, if waterproofing fails and moisture causes the face of the wall to discolor, the plaster may be stripped, the seepage repaired and the wall recovered to look like new. Comparatively, such a problem with poured concrete is disastrous. Poured concrete walls also offer the opportunity to achieve very creative and unique finishes.
The architect will specify the footing that will extend outwards from the face of the wall or out the back which will influence the planting at the base of the face of the wall. Drainage issues for lawns can develop if the footing is too large. It also prevents excavation of planting holes of shrubs and trees. For this reason, your designer will coordinate the footing size and dimensions with paving or planting that runs along the face of the retaining wall to accommodate any limitations.