A retaining wall is a concrete structure that holds soil at two different heights (made by cutting and filling) while resisting lateral earth pressure strains. Although the design of a retaining wall may appear simple, there is much more going on behind the scenes. If information, attention, and skill is lacking when building a retaining wall, danger looms large.
Retaining wall failures can result in expensive property and utility damage and catastrophic injuries, and even death. Therefore, it is preferable to have a retaining wall designed by an engineer and erected by a professionally licensed retaining wall builder to have a secure, efficient, and cost-effective retaining wall.
Here are the methods for building a small retaining wall, including a few things to remember about retaining walls. This isn’t a complete step-by-step guide. However, it will give you a fair idea of how the design process works and what you can expect.
The initial step in the design process is to choose appropriate soil types and attributes. Then, a retaining wall engineer can design the wall based on the soil-engineering parameters specified in the building regulations or refer to geotechnical research to determine appropriate design standards. A geotechnical analysis will lower an owner’s liability and, in many situations, result in less restrictive design criteria, reducing the cost of the wall system.
A geotechnical assessment may also reveal previously undiscovered subsurface conditions, such as expanding clays and perched groundwater, that must be included in the designs and construction.
More investigation is required when dealing with unusual wall configurations or unfamiliar soils. To determine whether a wall engineering design is required for your retaining wall project, consider the following factors:
What is the Wall’s Height?
Most governments will require a building permit and design from a licensed engineer if a wall is taller than 4 feet (measured from the bottom of the first block to the top of the final block).
Is There a Path Leading to Your Wall?
Look to see if the retaining wall is close to a pedestrian or vehicle route. Building codes typically demand a railing if the steep slope (or perceived elevation of the retaining wall) exceeds 2.5 feet and the pathway is within 3 feet of the top of the slope. If the retaining wall is taller than 6 feet, fencing or a handrail is required in all cases, unless there is another mechanism to restrict access to the top. If individuals are unsure whether the wall requires fencing or handrail, they should consult a retaining wall engineer. People may have to be responsible for themselves if they go off the edge of the wall.
Is There Going to be a Slope at the Top of the Retaining Wall?
A licensed engineer should be consulted if the top of the wall has a slope (the maximum in California is 2:1). They’ll look at the retaining wall surcharge and see if a design is necessary.
Is the Retaining Wall Going to Have a Terrace?
Because building a terraced wall is difficult, a set of guidelines must be followed. First, the terraced back wall should be placed back twice the height of the front wall, i.e., for a 3 feet front wall, the back wall should be placed back 6 feet. If the back wall is within that zone, the wall is considered one wall, and a 4 feet building permit is required. Furthermore, the back wall must be shorter than the front wall. Consult a licensed engineer for advice and a design.
Will There be Parking for Automobiles, Trailers, Motor homes, and Other Vehicles at the Top?
Consulting a licensed engineer is a must before a heavy vehicle can be parked on or near the top of a wall. Car parking, concrete, and snow loads can place a lot of strain on retaining walls, so seek an engineer’s assistance. In addition, because wall problems may not show up until the rainy season, consulting with a professional engineer can help develop a strategy to reduce the likelihood of troubles.
Is the User from an Earthquake-prone Region?
In a seismic zone, a structural engineer should inspect all retaining walls. Earth-retaining structures should be constructed to withstand seismic forces in two situations:
- When a retaining structure fails or deforms severely, it may result in the death or injury of those inside the building and the loss of amenities. This applies to walls that are less than about 10 feet high.
- When the retaining structure’s effective height surpasses approximately 10 feet within a horizontal distance of 1.5 times the retained height, this height includes the foundation above or below the retaining structure.
Is There a Source of Water Nearby?
Even if the wall is only temporary, consult an engineer if it will be built near a lake, river, or other water sources. It might be a huge concern if irrigation lines, water lines, or any other high-pressure water bodies begin to spill or burst. As water is the most common cause of retaining wall collapses, people must take extra steps to maintain the wall safe.
“It is far better to do something right the first time than to fix it later,” a wise man once said. Not only are retaining walls attractive, but they also serve a practical purpose. They can support the structural integrity of a project. If you want to construct one, keep in mind that the foundation and other structural components may require additional protection from surface runoff or flooding. Seek professional assistance if necessary, choose appropriate building materials, and protect the property from structural failure.
How can Design Everest Help?
Every structure is unique; thus, consulting a professional wall designer is crucial to determine the best solution to a given problem. However, we’ve got you covered when it comes to retaining wall project planning and licensing. Design Everest’s expert retaining wall planners can assist you with all your requirements. Contact us today for more information.