Yards often have some degree of hilly terrain, and it is often desirable to accentuate this vertical
dimension by the use of a landscape retaining wall. This terraced look adds another layer of
interest to any landscape. Typical materials used for this purpose are stone, wood, and pre-cast
concrete blocks (made by the same companies that provide the concrete pavers.) Following is a
brief description of each.
Stone walls can be built by using either natural rounded boulders, or by stacking a flat, split stone.
They are further classified as either “dry laid” or “mortared” (see mortared walls below).
Boulder walls (most commonly made of Michigan fieldstone) are constructed simply by
lining up boulders in a row and stacking them up if a higher wall is desired. Northern
Hardscape, located here in Michigan, has a nice website for examples of this type of
product. These walls are simple and natural in appearance, and often the most cost effective
solution. While they do last a long time, they are not as structurally stable as some other
walls due to the large gaps created by the irregular shapes of the stones. Dirt can slowly
wash out between the gaps.
Split stone walls can be built of any of several types of natural stone which have been either
naturally split or saw-cut to form large flat pieces suited for stacking. Common examples
include sandstone, flagstone, and grindstone. Units can be as thin as 2” or as thick as12”,
depending on the scale of the wall desired. These stones are laid in a level fashion, thus
imparting a more structured and refined appearance to the landscape, and are more stable
than their boulder counterparts.
Wood walls are constructed almost exclusively of large pressure treated timbers – also known as
railroad ties. Common sizes are 4”x4”, 4”x6”, 6”x6”, and 6”x8”. Most come in 8 foot lengths.
They are simply stacked and secured with nails or screws. They are very structurally stable and
present a more clean and structured look due to their straight and level appearance. Somewhat
objectionable characteristics include their unsuitability in creating curved shapes, as well as their
relatively limited lifespan (typically ten to twenty years.) Wood retaining walls are usually the most
cost-effective.
Pre-cast concrete retaining walls are made of blocks manufactured in a similar manner to
concrete interlocking pavers. (See the paver websites.) They range from small to large pieces,
depending on the height of the wall you want. They are engineered to be installed on the level,
over a crushed stone or sand base, and each unit is designed to tie into the unit stacked below it,
thus creating a stronger wall. Pre-cast walls also offer a wide variety of styles and colors, allowing
the designer to create anything from a smooth, straight, formal look to a textured and curved wall
with a natural flavor. And because these walls are dry laid, precisely engineered, and built on a
gravel base, they are flexible, yet very stable and long-lasting. Naturally, they cost more as well.
Mortared walls (or masonry walls) are differentiated from dry laid walls by two main factors.
First, they require a 42” deep, frost-free concrete footing. Second, the wall itself is layered (using
most any type of brick or stone) with mortar joints between the units. Mortar is a rigid material,
with no give, and would quickly crack and deteriorate without its deep, stable footing. Mortared
walls are beautiful and durable, but they also carry the highest price tag of all retaining walls.
All retaining walls and steps we build are backed by our solid, no hassle One Year Warranty.
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