In the Delaware Valley, uneven terrain is quite common. A sloping backyard makes creating a flat area for outdoor activities such as games, picnics, or just “hanging out” challenging. Retaining walls offer a practical solution to this problem.
If the backyard slopes down and away (see diagram below), the retaining wall is built at the point where you want the yard to stop. The area between the slope of the yard and the wall is filled in and becomes yard. On the other side of the wall, the slope can remain on the ground and can be leveled to create another lower flat area.
If the backyard slopes up (see diagram below), the retaining wall is still built at the point where you want the flat yard to stop; but, in this case, excess ground is removed. The area behind the wall is then filled in.
In both cases, the wall has significant retaining responsibilities: The distance equal to two times the height of the wall behind the wall is the area exerting pressure on the wall. So, if the wall is three feet high, six feet of ground is being retained. If the wall is five feet high, retention is 10 feet of ground.
Products vary in their ability to retain. The maximum height that can be built without special engineering with traditional retaining wall blocks is four feet. This type of block will generally weigh between 60 and 90 pounds each and create a wall approximately 12 inches thick. Examples include CST Versa Lok block, EP Henry Mesa and Diamond Pro block, Techo-Bloc Suprema. A few specialty products exist which are significantly larger and heavier and can build substantially larger walls, e.g., Techo Bloc Monumental.
Retaining walls designed to reshape the contour of an outdoor living area have many technical requirements. Do not undertake this type of project for walls over 3 feet high without using a contractor with specialized expertise.