Retaining Wall Engineering

Retaining walls are a surprisingly common neighborhood feature, but you might not even realize they’re there. Retaining walls allow us to build and live on uneven surfaces by stabilizing the slope of the landscape, ensuring the weight of the earth stays in place and remains stable. This lets us safely build on uneven ground, whether it’s a house or just your landscaping. Because a wall deals with such strong forces, however, they need to be created correctly for each lot.

There are many different types of retaining walls you can add to your home or business property. It is critical, however, that all retaining walls are designed by a licensed professional structural engineer. Collapse or failure can lead to serious property damage or human injury.

Xpress Engineering can quickly and safely provide a custom engineered retaining wall design for your project at an affordable cost. Whether you are a homeowner, architect, designer, or contractor, we can design your next retaining wall quickly, professionally, and inexpensively.

What Are Retaining Walls?

As a concept, retaining walls are very simple. Technically, they can be made to retain anything – even a dam wall is a retaining wall, talking technically. However, in home or landscape construction, retaining walls have a specific function. They’re relatively low walls introduced to an uneven ground for stability.

Retaining walls stabilize the earth on the higher part of the slope, so it can’t slide downgrade due to gravity. They also generally help protect against soil erosion and slope failure.

Structural Engineer for Retaining Wall Designs

Why do you need a structural or civil engineer for such a simple project? While the idea is simple, the actual construction is not. A lot depends on what is going to be behind the wall.

You may need a short retaining wall which helps you create an aesthetically pleasing garden. Or you may need a very strong retaining wall correctly engineered to the specific site conditions. No matter what the purpose, the idea is to create a retaining wall that isn’t just pretty, but has the strength in the right places to keep everything in place.

Structural Engineer

Your retaining wall must be made of the right materials, have the correct proportions, be sized correctly for the type of retained soil, and have drainage that suits the weather and use.

It must resist the soil pressure, hold up to the weight, and last through all types of weather. Designing retaining walls is an art that requires the eye of trained structural or civil engineers who understand the forces at play.

A skilled design engineer is a critical element to insure the success of your project!

Engineered Retaining Walls

Cantilever retaining walls are one of the most common designs, especially for landscapes, although there are a few other types of retaining walls. “Cantilever” refers to the wall being supported by a footing below it, but nothing at the top. This is the type of retaining wall that we design for our clients, using a variety of retaining wall materials: concrete, CMU blocks or wood.

So, where nature would otherwise send earth sliding down from the earth’s lateral forces, the wall is created to withstand these forces. It’s width and heaviness are both important. Similarly, it’s important to build the correct wall height for the purpose, and to construct it properly.

When designed with the right engineering skill and built properly, your retaining wall will be stable and hold the soil back with the strength and stability necessary to control the natural slope. Everything is kept in perfect balance.

Drainage for retaining wall

Retaining Wall Drainage

Site conditions aren’t the same all the time. Rain and other precipitation happens. Gardens are watered. And wet soil is exponentially heavier than dry.

In fact, wet soil failure is one of the most common causes of failures in retaining walls! That’s why your engineer or landscape architect might recommend a series of retaining walls in layers for your garden, even if the area seems stable to the eye.

This means the materials and construction of the retaining wall must stand up to the heaviest forces it will endure. Drainage is a critical element to consider.

Typically, the site is prepared with the necessary drainage in mind. This may vary based on the exact purpose of the retaining wall and the engineering needed. However, backfill of stone and gravel is commonly added to the ground behind the wall to insure stability.

Technically, the term ‘backfill’ refers to anything returned to the higher side of the wall. Soil is dug out during construction, and replaced after the retaining wall is in place.

However, to reduce hydrostatic pressure and help with drainage, gravel and stone drainage material are normally added as a foundation for the backfill, and top soil is then added to the top third to complete the backfill.

Drainage paths and features such as water tiles, drains, and dry wells may also be required.  Proper drainage for the site is a key part of the construction design of your retaining wall.

Retaining Wall Anchors

The footing of your wall is where a great deal of its strength resides. Put simply, footings are the part of the retaining wall design you don’t see.

Footings lie under the soil, deep in the site, but perform a critical function. All the same, for some sites, even the toughest footings may not be enough to resist lateral earth pressure.

While using the right backfill and gravel to assist water run-off can do a lot to help, sometimes you need additional strength. This is one of the many responsibilities of the design engineer for your wall.

Anchors for retaining walls

In some cases the engineer will recommend using retaining wall anchors. These are long rods driven through the retaining wall and attached to anchor points on the other side. This helps to strengthen the wall and creates a better distribution of load over the surface.

Ideas for Your Retaining Wall Design

Once you know you have the correct construction materials and design for the size and height of your wall, you can consider the aesthetics of your retaining wall. There are a great many ways to enhance a site, and your wall installation doesn’t have to be functional alone – it can also be gorgeous.

Creating a look you’re happy with is a key part of retaining wall construction. Your contractor should consider the existing walls, the house, landscape details and your design preferences as well as the proper methods of construction.

What is the Best Type of Retaining Wall?

There are many types of retaining wall, as well as different materials that can be used, and each can be considered.

Concrete is tough, and will last for decades without rotting. Concrete is also very versatile. Concrete dyes let you create a variety of looks, and you can also texture concrete or use imprinted concrete to copy stone or create the illusion of blocks. You can even add a gravel, stone or brick veneer to simulate nature or improve compatibility with surrounding structures.

Poured concrete retaining walls are particularly suitable for the popular cantilever retaining wall design (used by Xpress Engineering), and they’re very tough as well. They can even be reinforced with steel for a stronger design. While concrete is a great choice for a retaining wall, and one that can be created in a variety of shapes to suit your site, there are other construction materials you can consider as well.

Another popular choice is a CMU block retaining wall design. There are various types of blocks available, which may be referred to as cement blocks, cinder blocks or CMU’s (Concrete Masonry Units). Any of these types of block can provide excellent materials for commercial, municipal, industrial, or residential retaining walls.

A CMU block wall is suitable for many purposes, but because of the modular components, they generally aren’t quite as tough as poured concrete. The most typical block used is a large, hollow, and lightweight concrete (or “cinder”) block. This type of block is both strong and durable, and can be reinforced for greater strength.

Wood retaining walls can offer a more casual style, and are especially suited for smaller and less demanding residential landscapes.

Xpress Engineering can provide professional retaining wall designs for CMU blocks, poured cement, and also for pressure treated wood retaining walls as well.

Solving Problems with Retaining Walls

Once you know you have the right construction and appearance for your retaining wall, you’re well on the way to solving your landscaping problems. But how do people use retaining walls? Let’s take a look.

Sloped Back Yards

Most of us consider our back yards the heart of the home. You want a place where you can have fun and live in. On a gradient, however, you may encounter many issues. Rain may pool or flood. Flower beds may become unstable. Or you might not have a nice place for a fire pit, BBQ, or entertainment area.

Imagine how beautiful a stone block fire pit could look with a retaining wall faced with the same material. Or how much more you can get from your garden with an attractive retaining wall in the background to build the flower garden of your dreams.

Sloped Front Yards

Your front yard is the face you present to the neighborhood. You want it to be beautiful! Attractive concrete or block retaining walls, especially with an attractive facade or surface, can turn a dull uphill trek to the front door into a cascade of beautiful layers of lawn, flowers, and maybe even a gravel bed or stone path.

A Driveway Retaining Wall

When your property isn’t flat, creating a driveway can be a hassle too. Smart use of a well-designed retaining wall can allow you to level part of your site for a driveway without it flooding in the rain.

Retaining Wall Fences

Of course, a retaining wall can be used as a fence alternative, or paired beautifully with a fence above the wall, for added privacy. Even out height disparities between your site and the neighbors, make your boundary look spectacular, and/or provide more room for landscaping. Smart backfill and drainage can help redirect rain, too.

Entertain with a Patio Retaining Wall

Just as you can create a freestanding entertainment area, you can use a beautiful retaining wall to lead to your patio. A well designed retaining wall can look great for this purpose.

Build the Perfect Retaining Wall Fast with an Xpress Engineering Design

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