Retaining Wall Failures: Common Causes & Lessons Learned

From suburban landscaping to large-scale commercial developments, retaining walls are indispensable. These civil structures are used to maximize usable land, manage changes in elevation, and control soil erosion. Despite their widespread use and history, retaining wall failures sometimes result in significant property damage, personal injury, or loss of life.

Such collapses can often come with significant financial and legal consequences, frequently leading to complex insurance claims and litigation. For legal and insurance professionals, identifying the root cause of a failure is often central to evaluating liability, challenging opposing experts, and developing an effective case strategy. 

Understanding the engineering factors that contribute to these failures is essential for accurately assessing liability and implementing effective risk mitigation strategies. 

Retaining wall failures can arise from a combination of engineering factors and site-specific conditions. While each case may present unique challenges, most failures can be traced back to a few recurring issues. This article explores the four most common causes of retaining wall failures we typically see in our practice and key lessons learned from past incidents.

Design Deficiencies

A properly engineered retaining wall begins with a strong design. These structures need to be carefully planned to withstand the lateral pressures from the soil behind, the added force of water buildup (hydrostatic pressure), and any additional weight from adjacent structures, vehicles, or sloping ground conditions. 

If any of these forces are not considered appropriately, the walls may bulge, crack, or even collapse, sometimes without warning. In Georgia, for example, the current residential building code based on the International Residential Code mandates that any retaining wall over 48 inches tall, or those exposed to groundwater or supporting additional loads, must be designed by a licensed professional engineer.

In many forensic investigations, design flaws or lack of a design are a recurring issue in wall failures.

Common issues include: 

• Undersized or missing footings
• Lack of structural reinforcements like tiebacks
• Absence of proper drainage features

These oversights can compromise the wall’s ability to perform under the expected conditions. Ultimately, neglecting proper design can lead to not only costly engineering failures, but also serious legal repercussions.

Drainage Failures

Water is often considered the silent threat to retaining walls. While these structures are built to hold back soil, they are usually designed to relieve hydrostatic pressure and thus do not consider the additional forces created by trapped water in the design. 

When drainage systems are missing, poorly designed, or clogged, water can accumulate behind the wall much like behind a dam, generating hydrostatic pressure that significantly increases the load on the structure. This added pressure can quickly exceed the wall’s design capacity, leading to bulging, cracking, or sudden collapse. 

These failures often follow a familiar sequence: 

• Heavy rainfall
• Inadequate drainage
• Pressure buildup
• Eventual structural failure

This can be critical when reconstructing events and evaluating competent expert opinions. To prevent such outcomes, effective drainage design, construction, and maintenance are essential.

A typical system includes a perforated pipe at the base of the wall to collect and redirect water, gravel backfill to promote flow, and weep holes to relieve pressure on the wall’s face. These components work together to ensure water does not become a hidden hazard. Investigations often reveal that drainage was either overlooked or improperly implemented, making it a key factor in determining liability. 

Ensuring proper water management is not just good engineering; it is a critical step in reducing risk and avoiding costly disputes.

Construction Defects

A retaining wall’s success depends not only on sound design but also on proper execution during construction. Mistakes made on-site, including poor workmanship, the use of low-quality materials, or failure to follow the approved plan, can significantly weaken the structure. 

Common issues include: 

• Loosely compacted backfill
• Misaligned wall units
• Insufficient reinforcement
• Missing critical elements like drainage components or structural ties

These issues may not be immediately visible but can lead to gradual deterioration, especially when the wall is exposed to environmental stressors like heavy rainfall.

From a legal and insurance perspective, construction-related deficiencies are frequently identified during forensic evaluations following a failure. When contractors deviate from design specifications or substitute materials without proper authorization, they may inadvertently create conditions that compromise the wall’s integrity.

These oversights can result in expensive repairs, insurance claims, and legal disputes, particularly when the work does not comply with building codes or accepted industry practices. Ensuring quality control, conducting thorough inspections, and adhering to engineering documentation are essential steps in reducing the risk of failure and associated liabilities.

Soil & Site Conditions

The long-term performance of a retaining wall is heavily influenced by the characteristics of the surrounding soil and the conditions of the site. When these factors are not properly assessed, the wall may be exposed to unexpected demands that compromise its stability. 

Certain soils, such as expansive clays, can swell significantly when wet and shrink during dry periods, creating movement that places uneven pressures on the wall. Similarly, soils with low shear strength, meaning they lack internal resistance needed to prevent shifting or sliding under pressure, or those with high moisture content may not provide adequate support. 

This is particularly important when such conditions are combined with sloped terrain or fluctuating groundwater levels. Over time, site conditions may change due to natural erosion, nearby construction, or altered drainage patterns. These changes can complicate causation analyses, particularly when failures occur years after construction. 

Without a geotechnical investigation during the planning phase of new construction, these risks may go unnoticed until signs of distress begin to appear. Comprehensive geotechnical studies that include soil borings and laboratory testing are commonly recommended by the design engineer to identify potential risks before construction begins. 

In many failure cases, the absence of proper soil testing or the misinterpretation of site data has been a key factor. Understanding ground conditions is not just a technical requirement, but also a foundational step to ensure the safety and reliability of any retaining wall system.

Retaining Wall Failure Prediction & Prevention

Retaining wall failures can arise from a combination of design missteps, constructions flaws, inadequate drainage, or overlooked soil conditions. Each of these factors introduces vulnerabilities that, if not addressed, can lead to costly structural damage, legal disputes, and insurance claims.

The key takeaway is that retaining wall failures can be foreseeable and preventable when projects are performed by qualified expertise, thorough planning, and good execution. This means: 

• Involving experienced professionals early to assess site conditions, soil behavior, and loading requirements, ensuring that the design is proper and resilient
• Careful planning that considers long-term performance, including proper material selection and drainage strategies
• Proper engineering design, thorough geotechnical investigation, quality construction practices, and effective water management

For legal and insurance professionals, understanding the causes behind a retaining wall failure provides a framework for evaluating causation, identifying responsible parties, and challenging unsupported expert opinions.

It also offers valuable context when evaluating liability, assessing claims, or advising clients. Early involvement of qualified experts can help preserve critical evidence and clarify technical issues before they become disputes.

When retaining wall failures lead to property damage, injury, or litigation, the right technical expertise can make all the difference. ESi's consultants have extensive experience in construction-related failure investigations, from evaluating design adequacy and drainage systems to assessing soil conditions and construction quality. Explore ESi's construction expertise.