What Are The 10 Most Common Mistakes People Make When Building Retaining Walls?

Key Takeaways

• Proper planning and site assessment are crucial to avoid costly mistakes and ensure your retaining wall performs well in diverse American soil and climate conditions.
• Perhaps the most basic need in retaining wall construction is proper water management. Thompson says that including proven drainage practices in the construction phase will protect the wall from failing from hydrostatic pressure or erosion.
• Selecting appropriate materials and creating a solid foundation are crucial processes. Using subpar materials and inadequate footings will lead to a structurally unsound wall. This problem is particularly acute in areas with high precipitation or earthquake risk, such as California.
• Following proper construction techniques dramatically improves wall longevity. Things such as full compaction and adequate reinforcement help minimize future maintenance as well.
• At the very least, following local building codes and getting the appropriate permits will keep you out of legal hot water. This helps assure your wall is built to regional safety standards.
• Periodic inspections and maintenance allow you to identify problems such as cracking or leaning before they become serious. This proactive approach saves you money by extending the lifespan of your retaining wall and protecting your investment!

Don’t be one of the 10 most common mistakes when building retaining walls in the United States. These mistakes result from inadequate planning, choosing inappropriate materials, and not understanding the local soil conditions.

Too often, they neglect drainage or don’t establish a good base, causing retaining walls to settle or buckle prematurely. Others will try to cheap out and use blocks or wood that aren’t meant for outside, and guess what?

Failure to consult city regulations or failure to call for utility locations before excavation leads to a disaster down the road. Still others construct walls too high for their expertise.

Or they use the wrong type of backfill behind the wall, which pushes against and makes the wall lean or tip. By understanding these common pitfalls, you can prevent expensive rectifications and ensure that your wall remains sturdy and secure.

The following sections explain each mistake, how to identify them, and how to avoid them.

Top 10 Retaining Wall Blunders

Retaining walls may seem easy to construct, but a lack of attention to detail at the outset can lead to disastrous consequences down the road. Many homeowners and some contractors, too, often skip or overlook the most critical steps. They forgo the planning process, resulting in walls that have compromised performance far too early.

Steering clear of these common retaining wall blunders will save you time, money, and headaches in the future. Below are the top ten mistakes that we find people make when constructing a retaining wall. Avoiding these common mistakes will help build stronger, longer-lasting walls.

This experience will equip all of us to design with greater foresight and avert such issues in the future.

Ten Common Retaining Wall Mistakes:

• Skipping essential groundwork prep
• Ignoring water drainage needs
• Choosing the wrong wall materials
• Building on a weak foundation
• Forgetting about frost heave
• Underestimating backfill pressure
• Incorrect reinforcement installation
• Rushing the construction steps
• Cutting corners to save money
• Overlooking local permit rules

Careful planning and attention to detail can go a long way in each of these areas. Walls that avoid these missteps last longer and perform better.

1. Skipping Essential Groundwork Prep

Even the widest, tallest, sturdiest wall cannot overcome poor prep work. Many projects fail right at the start, where people rush into building without checking the soil or planning the base. Key groundwork steps are testing the soil to ensure it’ll hold the wall’s weight, removing any unstable, soft topsoil, and excavating to the proper depth.

Basic steps include compacting any loose soil found in the fill area and ensuring the base or footing is level. In areas such as the Bay Area, soil conditions can vary drastically even from side to side in a yard. If you skip these steps, your wall may end up tilting or sinking.

A wall properly constructed on inferior prep might initially appear satisfactory, but will eventually begin cracking or leaning. Good groundwork involves selecting the best base material, too, like crushed stone, which promotes drainage and prevents shifting.

2. Ignoring Water Drainage Needs

Water is the biggest unseen danger for any retaining wall. Without proper drainage, water will accumulate behind the wall. This pressure exerts a tremendous force against it, leaving it vulnerable to failure.

Common drainage fix involves adding perforated pipes, or French drains, and using gravel backfill. Weep holes located at the base of the wall work well too. In areas with high moisture or clay soils, these areas of consideration are critical.

Walls built without consideration for water drainage tend to bulge or collapse and can even trigger sinkholes or erosion at the wall’s base. In other words, incorporating drainage from the beginning is much less time-consuming and costly than attempting to rectify water issues post-construction.

This is one of the smartest moves you can make to ensure the long-term health of your wall.

3. Choosing The Wrong Wall Materials

The right material for the job is crucial. Retaining wall materials must be suitable for the intended use and local environmental conditions. Concrete blocks, poured concrete, stone, and wood are just a few options available to choose from, each with its advantages and disadvantages.

Concrete blocks are well suited for building dead straight walls and for an industrial or contemporary aesthetic. If too much water accumulates behind them, they can crack. Natural stone blends into the landscape and lasts well, but it needs skill to install and can shift if not set right.

Wood is cheaper up front, but it decays more quickly in wet environments. In the Pacific Coast region, it can go from drought to deluge on a moment’s notice. Accordingly, concrete and stone typically outlast wood.

Selecting appropriate materials based on the environment and intended purpose will give the retaining wall a longer lifespan. This method makes maintenance easier!

4. Building On A Weak Foundation

As with most things, a weak foundation is a top reason for wall failure. Whatever the reason, indications of weak soil may be an abundance of clay, sand, or loose fill dirt, which are prone to shifting. This is especially prevalent in hillside communities.

Reinforcing a foundation usually involves excavating further down, adding in layers of compacted gravel, or pouring in a concrete footer. In more intricate or heavier-load applications, geogrid mesh or tiebacks come into play.

Building the foundation correctly from the start is much easier than addressing a crumbled wall down the line. For especially difficult soil, a geotechnical engineer’s counsel can save you the expense.

5. Forgetting About Frost Heave

Frost heave is an issue in areas that experience ground freeze during the winter months. When soil goes through these freeze-thaw cycles, it causes the soil to expand and then contract, pushing retaining walls out of alignment or even cracking them.

Walls constructed too shallowly have the greatest probability of failure. To do this, excavate the base of the wall below the frost line. Otherwise, be sure to use materials that can flex a bit without cracking.

In San Francisco and other such mild-climate cities, this is seldom a problem. For anyone developing in the Sierra foothills or our northern states, it’s something you must prepare for. Gravel and other free-draining materials in the base do a good job of preventing frost from heaving the wall.

6. Underestimating Backfill Pressure

Backfill pressure is the lateral load from soil and water behind the wall. If the wrong backfill is used or if the backfill isn’t properly compacted, then the wall can bulge or lean forward.

Best practice is to use gravel or crushed stone immediately behind the wall and properly compact each lift. It’s important to note that backfill materials, such as clay or loamy soil, retain water and will expand.

This added pressure can both crack and cause the wall to creep over time. For particularly high walls, geogrid mesh or other reinforcements are used to extend the load further into the earth and maintain the wall’s structure.

7. Incorrect Reinforcement Installation

Reinforcement is an essential aspect of wall strength, mainly in walls taller than three feet. Common errors involve not enough reinforcement, in the wrong locations, or choosing the incorrect type altogether.

For instance, you need to space and place steel bars (rebar) correctly in the concrete. Moreover, embed the geogrid mesh into the backfill at determined intervals.

When these steps are bypassed, the integrity of the wall is compromised and can lead to catastrophic failure under load. No excuse, especially since manufacturer installation guides are a primary go-to resource, and failure to follow them is what frequently nullifies warranties.

8. Rushing The Construction Steps

Constructing a wall cannot be done instantly, and rushed steps will create hasty decisions and errors. Other risks involve simply not allowing the concrete to set. Or you might skip level and alignment checks, or forget to compact each course of backfill.

These shortcuts save a few hours on-site today, costing an inconsistent wall, cracking, or even catastrophic failure down the line. Thoughtful construction, with inspections at every step, leads to a more durable wall and less maintenance down the road.

9. Cutting Corners To Save Money

Cutting corners to save money on materials, drainage, or base prep invariably comes back to bite you. Mediocre craftsmanship results in costly fixes down the line. Effective walls require quality blocks or stone, proper drainage, and good base preparation.

On smaller budgets, designs that are less complex—fewer curves or fewer steps—save money without sacrificing structural integrity. Buying materials in bulk or recycling pre-used stone can cut costs as well.

10. Overlooking Local Permit Rules

Most municipalities or counties have requirements for permits for a retaining wall beyond a certain height, usually three or four feet. Avoiding the permit process can result in hefty fines, required removal, or legal action.

In addition to establishing height limitations, local codes might dictate requirements for setbacks, drainage, and wall appearance. Asking your city or county before you begin is a good move.

Local building departments and planning offices provide useful guides and checklists to assist with this important step.

Select Materials Wisely

Selecting the appropriate materials for a retaining wall involves more than just selecting an attractive aesthetic. It’s not just about planning an outdoor space! It’s an art that needs to combine project requirements, site context, and budget constraints.

A few practical points can help guide decisions:

• Local climate and soil type
• Wall purpose (height, load, drainage)
• Strength of each material
• Aesthetic match with nearby structures
• Availability in your region
• Upfront cost and long-term upkeep

Matching Materials To Your Project

Each project will have different requirements. For a garden bed wall, naturally rot-resistant wood or modular block may be appropriate. For a very tall wall retaining a steep hillside, you will likely want poured concrete or reinforced masonry.

Your local climate should play a role as well. Freeze-thaw cycles in colder areas can crack softer stones or concrete if not properly engineered. In wet environments, wood can deteriorate quickly.

The color and finish of the materials further dictate whether the wall will become an amenity or an eyesore. We’ve found that it’s often good practice for anyone to consult with a local engineer. This helps to make sure that whatever they choose suits their intended function and aesthetic.

Durability VS. Cost Considerations

Materials such as stone and reinforced concrete are more expensive initially, but they withstand years of extreme weather and the stress of being on a major highway. Those cheaper materials, such as timber or bare blocks, are likely to erode more quickly and require greater repair.

The long-term savings argument for a higher initial spend, reduced repairs/maintenance down the line, justifies this higher fee. It makes sense to consider not only the initial cost you can bear today but also the long-term costs you will incur.

Avoiding Unsuitable Material Choices

Railroad ties and untreated wood eventually degrade or leech toxic chemicals into the surrounding soil. Unreinforced brick is prone to cracking when pressured.

Poor material selection could result in unsightly bulges or, worse, structural failure. Research the performance of each material before purchase and consult an expert familiar with local soils and codes.