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Creating a Level Backyard with Retaining Walls

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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.

Retaining Wall Down Woodward Landscape Supply

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.

Retaining Wall Up Woodward Landscape Supply

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.

Building a Wall Step 3: Contruction

Deciding Who Should Build Your Wall

You’ve taken the time to determine the structure and choose the look and feel of your wall, and now the time has come to actually build the wall you have been planning. The most critical question is, should you try to build it yourself, or not? Several factors should be considered in evaluating whether or not you should attempt this as a do-it-yourself project.

  • Technical difficulty
  • Risks or impact of making serious mistakes
  • Availability of time to work on the wall
  • Personal physical fitness
  • Enjoyment
  • Urgency of schedule to finish the wall
  • Access to needed tools and equipment
  • Cost
Assessing Difficulty and Risk

Assessing Difficulty and Risk

This diagram charts the relative technical difficulty and cost of mistakes of major hardscaping projects, including wall (shown in red) projects. Technical difficulty is based on knowledge needed to execute the project, complexity of the construction steps, breadth of tools and equipment needed, physical demands on the construction crew, and the need for specialists and/or permits during the construction process. In general, the higher the wall and the more stuff behind the wall, the greater the technical difficulty. The cost of mistakes refers to the kinds of problems that incorrect construction can produce. In the case of a sidewalk, a typical mistake will result in poor grading, puddles forming, and ultimately the need to redo the work. Physical harm is unlikely. In the case of a wall, the worst case scenario is that it falls down and destroys what it lands on. The cost is not only reconstruction but liability for injury and damage.

Assuming you can convince yourself that you are willing to deal with the technical and liability risks, the next thing to consider is timing. Do you have big chunks of free time to work on this project? Is there a deadline for completion (e.g., your daughter’s graduation party) that is going to put a lot of pressure on you to find time you don’t have or work in unpleasant weather conditions.

Then you should consider your health. Building a wall, even a garden wall, is a lot of heavy lifting. How’s your back? Do you really enjoy this type of physical effort and are you in condition to do this work without injury?

Finally, consider the costs. While it will definitely cost more out-of-pocket dollars to hire a contractor, there are hidden costs to doing this work yourself, including renting excavation equipment, buying or renting the special tools you need (e.g., laser levels), and potentially the cost of hiring a contractor to fix your mistakes.

A simple, flat garden wall is a doable project for almost anyone. But, once you introduce grade changes, products with complex installation steps, large heavy wall materials, or heights above 18″, it is time to look for a contractor. Our website offers a list of referrals for your assistance in finding qualified help.

Landscape Supply Tips – Building a Wall Step 2: Look & Feel

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Deciding How You Want the Wall to Appear

Regardless of the type of wall you want to build, you will find a huge selection of styles and colors in wall material. No matter where you find your landscape supply materials, manufactured wall block falls into two categories: Standard finish and aged finish. “Standard” products are characterized by square corners and a more consistent finish. “Aged” products are manufactured to look (obviously) old. Manufacturers may call this look antiqued, weathered, tumbled, or aged.

Standard finish products may be flat, split-faced, rounded, chiseled, or feature some type of beveling — all of these approaches produce a different visual impact in the final wall. Aged finishes also have a huge variety of looks. Given the significant variance in the visual results of different manufacturing processes, it is extremely important for you to see a sample wall before selecting the product. Although looking at an individual piece may help, you really want to see at least a small section of wall before selecting the finish you want.

Individual Vera-Lok Weathered and Standard Blocks

Individual Vera-Lok Weathered and Standard Blocks

Tiered Wall Resulting from Standard Finish Block

Tiered Wall Resulting from Standard Finish Block

Garden Wall from Versa-Lok Weathered Block

Garden Wall from Versa-Lok Weathered Block

 

 

 

 

 

 

 

 

 

As an example, the picture above shows a single Versa-Lok block with both a standard and a aged finish.  The next two pictures show wall built from each of these two finishes.

See the difference?

There are many factors in pricing the construction of a wall.  Looking only at the wall material itself, two pricing rules generally apply:  (1) the larger the individual wall block, the less the wall material will cost per square foot. (2) for a given shape, aged walls cost more than standard walls.

After selecting finish, the other major element of look and feel is color. Every mnufacturer offers a selection of colors and if you consider the color pallet of the industry, you will find an amazing selection.  Although you will find a few solid colors among your options, most products will be blends of two colors.  More recently, manufacturers are beginning to introduce tri-color blends.  It is not necessary to limit yourself to one color.  Although not as common as a homogenous wall, colors can be mixed.

Never select a color from a catalog or a website.  Wall materials are not glossy, they have a natural finish and it is extremely unusual to find a picture that looks a lot like the real thing.  See a sample or, ideally, see several.  Usually, color has no impact on price unless you want a special order color.

In additional to manufactured products, wall can be built from natural stone. Natural stone is significantly more inconsistent in texture and color.  It’s beauty is that inconsistency.  The price range for natural stone is huge.  Generally, the labor for natural stone will be higher than for a manufactured product.

One of the newest trends in wall products is manufactured products that simulate natural stone.  For an example, consider Techo-Bloc’s Muro Naturale.

When you have finished your look and feel investigation, you will have selected a landscape supply product or short list of products that will define the texture, finish, color and, as a result, the overall impression that your wall will make.

Building a Wall Step 1: Determining Structure

Understanding What Kind of Wall You are Trying to Build

You want to build a wall to enhance your outdoor living environment.  The first step is to determine the structural needs of your wall. It is the structure that dictates your construction technique, what construction materials and tools you need, and, perhaps most importantly to your finished project, what natural stone products you can successfully use to build the wall. The appearance of the finished wall will be determined by the wall material you choose. The issue of appearance, i.e., style, texture and color for your finished wall, will be covered in a separate article: Building a Wall Step 2: Look and Feel.

There are three major types of wall structures:
1. Garden walls
2. Retaining walls
3. Sitting walls.
The fundamental differences in these walls are their height and what is behind them.

A Garden Wall refers to a wall designed to define an outdoor area such as a flower bed, a tree, a mailbox, a lamp post. No higher than 18 inches, a garden wall generally holds in soil and may be topped off with mulch or decorative stone.  With a garden wall, you create a raised area that becomes a softscaping environment filled with whatever you want to create the visual impact you envision.  Options to complete your garden wall project include plants, boulders, statuary, fountains, birdbaths.

Garden Wall around Pond

Garden Wall around Pond

Literally any wall block or natural stone hardscape supply can be used as the garden wall has the least demanding structure.  Although any wall product is technically acceptable, the most common materials are small wall blocks or stacked natural stone.  Manufactured garden wall blocks include Coventry Garden Wall from EP Henry and Manchester from Techo-Bloc.  Most garden wall products are approximately 4” high x 12” long x 8” deep.   There may be a lip on the back of the block to lock each course as you build it up but many are simply stacked and held in place by weight.  Garden Wall products can not be safely used in either retaining wall or sitting wall applications. If the garden wall requires a greater height than 18 inches, products classified as garden walls can not be used as designed and you must use retaining wall construction techniques.

Retaining Walls are structures with the specific requirement of holding back large amounts of soil and/or rock.  Retaining walls are 2 feet up to literally as high as needed.  Commercial walls, e.g., the walls you see along the highway or around a shopping center, can be amazing heights.  Situations where a residential retaining wall (also known as an SRW) is necessary include:

  • Building a wall to eliminate a sloped back yard and create a large flat yard for outdoor activities or a patio or other outdoor use
  • Building a wall to protect your driveway by holding back soil that slides onto a driveway from a yard that is significantly higher than the driveway
  • Building a garden wall around the side of the house where the front yard is higher in the back yard so that the wall may be only 15” high in front but becomes over 2’ in the back
  • Building a wall to surround a walk-out basement
EP Henry Retaining Wall

EP Henry Retaining Wall

Retaining walls fall into two categories:  gravity walls or engineered (reinforced) walls.  Engineered walls require multiple skilled professionals to be safely executed.  A professional hardscaping contractor should be hired to build this type of wall as he or she will have the capability to arrange the technical resources needed for projects of this scale.  Gravity walls can be safely built by anyone willing to take the time to learn how.  Retaining walls can be built from manufactured segmental retaining wall block, stacked natural stone or boulders, and other construction materials such as Gabion baskets; however, very high walls require a suitable segmental retaining wall product.

A huge range of manufactured hardscape supply products are available to construct retaining walls (also known as SRWs).  Not all products are suitable for all heights and all applications.  Examples of SRWs suitable for modest height gravity-based SRWs elude EP Henry’s Terrace Wall and CST’s Versa-Lok Mosaic.  These products are at least 8” in depth and 6” in height and feature some locking mechanism Examples of SRW’s suitable for large scale gravity-based or engineered SRWs include:  Diamond Pro from EP Henry; Suprema from Techo-Bloc; and Versa-Lok from CST.

Sitting Walls are structures used to create a free-standing wall that can be used like a bench or for privacy.  Typical applications include:

  • Creating a sitting area on a patio or pool deck
  • Creating a boundary between two residences that are close together
  • Creating an outside perimeter on a raised patio to protect from falls
  • Creating an alternative to a railing on steps
Sitting Wall Bordering Patio

Sitting Wall Bordering Patio

Each sitting wall product has a maximum height which is usually between 24 and 36”.  Sitting wall products are the most expensive manufactured products due to the requirement for them to appear identical when viewed from either side.   Examples include: Mini Creta Plus from Techo-Bloc, Double-sided Coventry Wall from EP Henry, and Veranda from CST.

Please see the rest of the series on the construction of each of these wall types:

Building a Wall Step 2: Look & Feel

Building a Wall Step 3: Construction