Retaining Wall Failure: Causes and Solutions

Joe Lazzaretti
Jul 21
14 min read

Updated: Sep 2

When retaining walls fail, the consequences can be severe: property damage, safety risks, and costly repairs. The main culprits? Poor drainage, design flaws, and soil or environmental challenges. Water pressure is the most common issue, often due to inadequate drainage systems. Design mistakes, like miscalculated loads or low-quality materials, can also lead to failure. In regions like the Bay Area, soil movement and seismic activity further complicate matters.

Key Takeaways:

Warning Signs: Bulging, cracks, leaning, water seepage, and soil erosion.
Causes: Water buildup, poor design, and unstable soil.
Fixes: Improve drainage, reinforce structures, and use durable materials.
Costs: Repairs range from $100 to $1,500; replacements can cost $6,000 to $14,000.

Early detection and regular maintenance are essential to prevent failures. For earthquake-prone areas, seismic retrofitting adds critical stability. Always consult professionals for walls over 4 feet to ensure safety and compliance with local codes.

How to Build a Retaining Wall and 6 Reasons they Fail

Main Causes of Retaining Wall Failure

Understanding why retaining walls fail is key to avoiding expensive repairs and ensuring they last. While every failure has its own story, most issues boil down to three main causes: water-related problems, design mistakes, and soil or environmental challenges. In the Bay Area, these factors are often intensified by the region’s unique climate and geological makeup.

Water Problems and Pressure Buildup

Water is the leading culprit behind retaining wall failures. When water collects behind a wall due to poor drainage, it creates hydrostatic pressure that can overwhelm even sturdy structures. Proper drainage features - like V-drains, weep holes, and correct grading - are essential to prevent water from saturating the soil and building up pressure[3].

In the Bay Area, the seasonal cycle of dry summers and wet winters adds to the stress on retaining walls. During dry spells, soil contracts and pulls away from the wall, creating gaps. When heavy rains arrive, these gaps fill quickly, causing a sharp rise in pressure[4]. Rising groundwater levels, driven by climate change and sea-level rise, further complicate matters. These changes could double the land area at risk compared to coastal flooding alone and jeopardize thousands of contaminated sites managed by state and federal agencies[2].

"All of these sites need to be reevaluated because it's not clear that people are safe, and with each passing year, there is more risk." - Kristina Hill, associate professor of landscape architecture and environmental planning at the University of California, Berkeley[2]

While water is a major factor, poor design can also undermine a retaining wall’s stability.

Poor Design and Engineering Mistakes

Design errors, though less common when professionals are involved, can lead to disastrous outcomes. These mistakes often stem from working with incomplete or incorrect data on soil conditions, water tables, or load requirements[5]. Effective communication between property owners and engineers is critical to ensure all factors are accounted for during the design process.

Issues like miscalculated loads or inadequate reinforcement can make a wall unable to handle the pressures from retained soil and external forces[6]. Additionally, cost-cutting measures - such as using low-quality materials or skipping essential steps during construction - can worsen the problem[6].

Take Sarah, a homeowner in San Ramon, as an example. Her retaining wall was repaired multiple times by different contractors, but each fix only addressed surface-level issues. Underlying problems, like insufficient footings and poor drainage, were ignored. As a result, the wall kept failing.

"Every time it rains hard, sections start leaning again. I'm tired of throwing money at band-aid fixes." - Sarah, San Ramon Homeowner[7]

Eventually, the solution involved replacing the wall entirely with a properly engineered, poured-in-place concrete structure. The new wall featured deeper footings, an integrated drainage system, and design adjustments tailored to the site’s specific needs.

Beyond design flaws, the surrounding environment and soil conditions also play a big role in retaining wall performance.

Soil Problems and Environmental Challenges

Soil and environmental factors are critical to a retaining wall’s success, especially in the earthquake-prone Bay Area. Problems often arise from soil movement, water pressure, or subpar construction practices[1]. Expansive soils, for example, swell when wet and shrink when dry, creating fluctuating pressures that can cause walls to shift or fail over time[10].

Seismic activity adds another layer of complexity. In San Francisco, retaining walls taller than 3 feet require a building permit to ensure they can handle both soil pressure and earthquake forces[9]. Earthquakes can be particularly destructive. During a quake, the soil behind a wall may temporarily act like a liquid, significantly increasing lateral pressure and leading to sudden failure[8].

Other factors, like heavy loads from nearby structures, vehicles, or changes in the landscape due to new construction, can exceed a wall’s original capacity[5]. Urban development can also disrupt natural drainage patterns, redirecting water toward existing walls. These challenges highlight the importance of thorough geotechnical evaluations to guide proper design[5].

How to Spot Retaining Wall Problems

Catching retaining wall issues early can save you from expensive repairs and potential structural disasters. Most problems are visible if you know what to look for, so regular inspections are a must to address these issues before they escalate.

Warning Signs You Can See

Taking the time to inspect your property can uncover early signs of trouble. For instance, bulging or bowing sections on a wall are red flags. These outward curves often mean the wall is under more pressure than it can handle - usually because of water buildup behind the wall or insufficient reinforcement[13].

Another major concern is leaning or tilting. If a wall starts to lean, even slightly, it could signal foundation movement or too much back pressure[13]. Ignoring this can lead to bigger problems down the line.

Cracks in the wall are another warning sign, and their direction can tell you a lot. Horizontal cracks often mean the soil or water pressure is too much to bear, vertical cracks might be linked to erosion or settling, and diagonal cracks could point to foundation shifts or stress in specific areas[12][13]. What starts as a small crack can quickly grow, especially after heavy rain or freeze-thaw cycles.

Other things to watch for include water seepage, which shows up as damp spots, stains, or puddles near the wall - especially after storms. Soil erosion around the wall’s foundation can weaken its base, and soil separation, where gaps form between the wall and the retained soil, can indicate movement that disrupts balance and pressure[11].

Spotting these signs early gives you a head start in identifying the specific type of failure, which we’ll cover next.

Types of Wall Failure

Different types of retaining wall failures can help you gauge the severity of the problem and communicate effectively with professionals. Here are the most common types:

Sliding failure: This happens when the wall shifts horizontally due to too much soil pressure, often accompanied by cracks at the base.
Overturning failure: In this case, the wall tips over because the top pressure is too great or the foundation isn’t strong enough.
Bearing capacity failure: This occurs when the soil beneath the wall can’t support its weight, causing the foundation to sink unevenly. You might notice parts of the wall appearing stepped or uneven in height.
Structural failure: This involves the actual materials of the wall breaking down, whether from aging, weather, or poor design. For example, stone walls may develop loose blocks, and concrete walls can crack or spall.

A dramatic example of structural failure happened in May 2005 at Manhattan’s Castle Village. A 65-foot stone retaining wall collapsed after increased groundwater pressure caused a 150-foot section to shift about 2 feet before coming down. The wall’s failure disrupted the Henry Hudson Parkway and highlighted the dangers of ignoring such issues.

Understanding these failure types emphasizes the importance of catching problems early.

Why Early Detection Matters

Delaying repairs can lead to skyrocketing costs and serious safety hazards. Fixing a retaining wall can range from $100 to $1,500, but if replacement becomes necessary, you’re looking at costs between $6,000 and $14,000[11]. Addressing problems early not only saves money but also avoids emergency situations.

"Early detection of retaining wall issues ensures timely repairs, averting further degradation and possible structural failure."
Geostabilization International [14]

A failing wall is more than just a financial headache - it’s a safety risk. Collapses can cause injuries, damage vehicles, and create dangerous conditions for pedestrians[15]. If neighboring properties are affected, you could also face legal disputes and hefty settlements[15].

"Small issues can quickly snowball into major failures if not addressed promptly."
Wayne Farris, Atlas Piers of Atlanta [15]

The damage doesn’t stop at the wall. Soil erosion can destabilize nearby structures, and failing to meet local building codes can result in fines or lawsuits[15]. Spotting the signs early is a practical step toward preventing these complications.

Make seasonal inspections part of your routine - especially after heavy rains or freezing weather. Cold temperatures can worsen problems, as freezing water expands by about 9%, increasing pressure on the wall[16].

"Spotting signs like cracks or gaps early can prevent a damaged retaining wall, saving you both time and money."
Unlimited Drilling [16]

How to Fix Retaining Wall Problems

Once you've spotted early warning signs, it's time to address the root causes and stabilize the structure. The right fix depends on the specific issue, but most solutions fall into three key areas: improving drainage, reinforcing the structure, and choosing the right materials and methods.

Better Drainage Solutions

Water is the number one culprit behind retaining wall failures, so fixing drainage issues should be your first move. Poor drainage can lead to increased hydrostatic pressure, soil erosion, and material deterioration [18].

"The reason drainage is so important in a retaining wall is simply because the lack of proper drainage is the primary reason a retaining wall can fail." - Western Interlock [17]

Key drainage elements include perforated pipes, gravel backfill, weep holes, and filter fabric. Each plays a vital role in managing water flow and protecting the wall:

Perforated pipes: These pipes, installed at the wall's base, direct excess water away. To work effectively, they need at least a 2% slope [18].
Gravel backfill: A minimum of 12 inches of compacted gravel behind the wall helps water flow freely, reducing pressure on the structure [20].
Weep holes: Strategically placed holes allow trapped water to escape [19].
Filter fabric: This lining prevents soil particles from clogging the drainage system, ensuring long-term effectiveness [19].

When deciding on drainage solutions, consider the specific needs of your wall:

Solution	Best For	Maintenance Needs
Drainage Pipe Systems	High water volume, efficient removal	Periodic cleaning [21]
Drainage Boards	Simple installation, low upkeep	Minimal maintenance [21]
French Drains	Sloped or uneven terrains	Regular upkeep to prevent clogs [21]

Regular maintenance is crucial - keep weep holes and drainage outlets clear, especially after heavy rain, to maintain efficiency [19].

If drainage fixes aren't enough, it's time to look at structural reinforcement.

Strengthening and Structural Repairs

When drainage alone doesn't solve the problem, reinforcing the wall becomes essential. Here are some common methods:

Geogrid reinforcement: These polymer grids strengthen the soil behind the wall. Installed in horizontal layers between wall courses, geogrids extend into the soil to counteract lateral forces. The typical length is about 70% of the wall's height [22][24]. This method is ideal for spaces where gravity walls aren't sufficient [22].
Tiebacks: High-strength steel bars or strand anchors add lateral support. Installed through drilled holes and grouted in place, tiebacks are tensioned to handle significant loads [23].
Load-bearing reinforced soil walls: These modern systems combine multiple reinforcement techniques, offering a cost-efficient and quicker construction process compared to traditional methods [25].

For walls taller than 5.5 feet, professional engineering design is highly recommended. Even for walls between 3 and 4 feet, consulting a civil engineer can prevent costly mistakes [22][24].

Choosing the Right Materials and Methods

The materials and methods you choose can make or break the success of your retaining wall repair. Here's what to consider:

Purpose and structural needs: Determine whether the wall is primarily structural or decorative. Structural walls require stronger materials and more robust designs [26].
Soil and weather conditions: Conduct a soil analysis to understand how local conditions will affect the wall. For example, clay soils expand and contract with moisture, while sandy soils may need extra drainage solutions. Taller walls often demand heavier-duty materials and techniques, while longer walls might require expansion joints to prevent cracking [26][27].
Material options: Different materials serve different purposes. Here's a quick comparison:

Material	Strengths	Best Applications
Poured Concrete	Strong and durable [28]	Structural repairs, high-load situations
Interlocking Concrete Blocks	Lightweight, easy to assemble [28]	DIY-friendly repairs for moderate-height walls
Natural Stone	Durable and visually appealing [26]	Aesthetic repairs and long-term solutions
Gabion Baskets	Supportive with drainage benefits [26]	Repairs requiring flexibility and water management

"Choosing the right materials for your retaining wall design is crucial to its overall success and functionality." - Du-West Services [26]

Budget and maintenance: While treated lumber might be affordable and suitable for small projects, it requires regular upkeep to prevent rot. On the other hand, high-end materials like natural stone demand less maintenance but come with higher upfront costs [26].
Local codes and permits: Research your area's building codes and obtain necessary permits. These regulations ensure safety and set minimum standards for materials and construction methods [26][28].

Proper installation techniques are just as important as material selection. Plan the wall's layout and drainage carefully to ensure long-term performance [28]. And for walls over 4 feet high, hire a professional landscaper or mason to avoid costly errors and ensure safety compliance [28].

Prevention and Maintenance

The smartest way to deal with retaining wall problems? Stop them before they start. Taking a proactive approach not only saves money but also prevents a lot of headaches down the road. With regular upkeep and thoughtful planning, you can extend the life of your retaining wall - especially in earthquake-prone locations like the Bay Area. These strategies build on earlier repair methods and focus on keeping your wall stable for years to come.

Regular Inspections and Upkeep

As mentioned earlier, catching issues early is your best defense. Think of retaining wall inspections as routine maintenance - small efforts now can save you from big, costly repairs later. Regular checks are essential for spotting potential problems before they escalate into serious damage [29].

How often should you inspect? Aim to inspect your retaining wall four times a year - once before and once after each season [31]. Extreme weather, like heavy rainfall or frost, can wreak havoc on a wall in no time, so these seasonal checks are crucial for catching problems early [29][31].

What should you be checking? Walk along the entire length of the wall and focus on three main areas: the wall surface, the drainage system, and the surrounding soil [31]. Here’s what to look for:

Wall surface: Check for visible cracks, leaning, or bulging. Even small cracks can hint at bigger issues lurking below the surface [30].
Drainage system: Look for signs of water pooling or seepage. Make sure weep holes and drain pipes are clear of debris to avoid clogs [30][36].
Surrounding soil: Watch for erosion, gaps, or discoloration - these could signal water damage or soil movement [30].

Keep records and act quickly. Document any concerns with notes and photos so you can monitor changes over time. Remove roots, weeds, or other growth from cracks, and clear debris from drainage systems after storms. After heavy rains, inspect the wall again to catch early signs of drainage issues [36]. Redirect water sources like downspouts, use swales, and adjust land grading to keep water flowing away from the wall [36].

Earthquake Retrofitting and Deep Foundations

In earthquake-prone areas like the Bay Area, retrofitting is a must for protecting retaining walls. According to the Association of Bay Area Governments (ABAG), a major earthquake could displace thousands, making retrofitting a critical step for safety [35].

Why does retrofitting matter? It strengthens structures to better withstand the lateral forces and ground movement caused by earthquakes [32]. For retaining walls, this means adding reinforcements to handle seismic stress and protect the terrain they support.

"Retrofitting significantly lowers the risk of structural failure during seismic events, protecting occupants and assets." - Golden Bay Foundation Builders [34]

Retrofitting is far cheaper than rebuilding after an earthquake. The process involves assessing the wall’s current condition, identifying weak points, and applying specialized techniques to strengthen it [32]. This often includes reinforcing foundations, adding shear walls, and upgrading other structural components [33]. Combining deep foundations with retrofitting ensures the wall’s stability in areas with frequent seismic activity [32][33].

How to get started: Begin with a detailed seismic risk assessment tailored to your property’s location, soil type, and structural setup [33]. In San Francisco, retrofitting projects must comply with local building codes, which incorporate lessons from past earthquakes and the latest engineering advancements [33].

Work with experts. Consult structural engineers, architects, and retrofitting specialists familiar with the Bay Area’s seismic challenges. They’ll evaluate your property’s vulnerabilities and recommend techniques like foundation bolting or structural reinforcements to meet your specific needs [33]. Local retrofit programs can also provide guidance and, in some cases, financial incentives [33].

Golden State Shoring Services

When it comes to retaining wall design, maintenance, and seismic retrofitting in the Bay Area, expertise is everything. Golden State Shoring offers decades of experience in tackling the region’s unique challenges with tailored engineering and construction solutions.

What they offer:

Custom retaining wall designs: Golden State Shoring creates walls that account for local soil conditions, drainage needs, and seismic requirements. They use a mix of proven engineering methods and modern techniques like advanced shotcrete applications and soil-structure interaction analysis.
Seismic retrofitting expertise: With a deep understanding of the Bay Area’s earthquake risks, they specialize in preparing retaining walls to handle seismic stress. Their team assesses existing structures for weak points and develops reinforcement strategies designed for seismic zones.
Advanced foundation solutions: For properties with steep slopes, unstable soils, or complex drainage issues, Golden State Shoring’s expertise in deep foundation engineering ensures lasting stability.
Comprehensive service: From initial assessments to ongoing maintenance, Golden State Shoring manages every step of the process. Their services include shoring system design, underpinning solutions, and temporary support structures during construction or repairs. With their in-depth knowledge of Bay Area geology, building codes, and permitting requirements, they know exactly what works and how to get it done.

For property owners dealing with retaining wall challenges or planning new construction, Golden State Shoring combines technical know-how, local expertise, and a full range of services to deliver durable, long-lasting solutions.

Conclusion

Retaining wall failures often arise from avoidable problems like water pressure, poor drainage, inadequate design, and shifting soil. The silver lining? Knowing these causes gives you the power to address them before they escalate.

The stakes are high. Around 30% of retaining walls fail within just a few years, with repair costs ranging from $100 to $1,500 - or as much as $6,000 to $14,000 for a full replacement [11][13]. This makes prevention not just smart but financially wise.

Be on the lookout for warning signs such as bulging, leaning, cracking, soil erosion, or water seepage. Spotting these red flags early can save you thousands of dollars. Pairing seasonal inspections with proper drainage systems and durable, weather-resistant materials creates a strong foundation for ongoing maintenance.

For regions prone to earthquakes, like the Bay Area, seismic retrofitting is a must. The combination of unstable soils, steep slopes, and seismic risks requires expertise that goes beyond standard construction practices.

To ensure long-term stability, it’s crucial to work with experienced engineers familiar with local geological conditions and building codes. Their knowledge can make all the difference in safeguarding your investment.

In short, retaining wall problems can be avoided with timely maintenance and professional guidance. Regular inspections and expert input are your best tools for keeping your retaining wall - and your property - secure for years to come.

FAQs

How can I prevent water from causing my retaining wall to fail?

Managing drainage properly is key to avoiding water-related failures in retaining walls. Incorporate drainage systems such as weep holes or perforated pipes to alleviate hydrostatic pressure behind the wall. To further safeguard the structure, apply waterproofing materials to the wall's surface. This reduces water seepage and helps prevent moisture buildup, ensuring the wall remains stable and lasts longer.

How can I tell if my retaining wall needs seismic retrofitting, and what does the process involve?

If your retaining wall was constructed before the mid-1990s - before modern seismic standards became common - it might need an upgrade to withstand earthquake forces. Some warning signs that retrofitting could be necessary include visible cracks, leaning or bulging sections, or outdated construction materials and designs that weren't built with seismic activity in mind.

Retrofitting a retaining wall often involves several key upgrades: adding steel braces for extra strength, improving drainage systems to relieve soil pressure, upgrading the foundation for better stability, and reinforcing connections between structural elements. These measures help the wall better absorb and spread out seismic energy, reducing the chances of collapse during an earthquake. To figure out the best solution for your wall, it’s smart to consult a structural engineer who can evaluate its condition and recommend the right improvements.

What should you consider when selecting materials for a retaining wall in an earthquake-prone area?

When constructing a retaining wall in an area prone to earthquakes, the choice of materials is a game-changer. Reinforced concrete and steel stand out as top picks because they combine strength with flexibility - two key traits for handling seismic forces. These materials not only resist cracking but also help absorb and spread out the energy from tremors. Adding steel bars for reinforcement takes the wall's durability up a notch.

Equally important is a well-designed drainage system. This prevents soil from becoming waterlogged, which could compromise the wall’s stability when an earthquake strikes. By using sturdy materials and prioritizing proper engineering, you can significantly boost the wall's ability to perform under seismic stress.