For homes on uneven terrain, retaining walls can be of great importance both practically and aesthetically. When these walls begin to fail, they can pose a real danger to your property and wellbeing in several ways. Depending on where they are placed, they could pose risk to other people outside of your property and household.
Innovative Basement Authority is one of the most experienced structural and foundation repair companies serving Minnesota, North Dakota, and eastern Montana. If you have concerns about retaining walls on your property, we should be your call; our team will be on site to inspect and secure the wall quickly.
What is a Retaining Wall?
A retaining wall is pretty much exactly what it sounds like; a wall that is placed to retain or hold soil behind it. These are most commonly found in landscape gardening; properties that are built on uneven or steep terrain may use retaining walls to provide flat ‘levels’ within their garden or along driveways, terraces, and walkways. This makes the space more practical for things like outdoor seating and can also be rather beautiful. Retaining walls are also common along roadways, parking lots, and bodies of water, and they have many applications. These walls can be built of many materials from wood to brick to carved stone, and even concrete.
How Retaining Walls Are Designed
Understanding the factors that go into the design of a retaining wall can help immensely while trying to identify the potential causes of damage and failure. The main concern when building a retaining wall, of course, is what is going to be behind it. If it’s simply in place to create a flat surface for a driveway, for example, then almost any kind of wall could be constructed, but if you have a pool the weight of the structure and water may require a specialist gravity wall. Other considerations are:
- Soil makeup
- Angle of the incline
- Presence of stone or boulders in the soil
- Required height of the wall
- Road access
Common Causes of Failure in a Retaining Wall
Considering how complex the process of design and installation is, it should not be surprising to hear that the single most common cause of retaining wall failure is poor design. Of course, this can take several forms. Aside from a design or construction flaw, retaining walls are subject to the same pressures as basement and foundation walls and as such can face many of the same issues that cause the need for foundation repair. The most common causes of failure are:
- Improper Reinforcement
If the level of wall reinforcement required is miscalculated during design or poorly implemented during construction a retaining wall can begin to fail very quickly. In this case, cracks can quickly become bulges and a total collapse of sections of a wall is very possible.
- Lack of/Not Enough Weep Holes
Weep holes are placed in every retaining wall but are particularly important in wetter or more humid climates. Properties in Minnesota, North Dakota, and eastern Montana will find that weep holes are crucial, especially in winter. A lack of weep holes will prevent water from draining out of the soil behind a wall and add extra weight as well as increased dampness, both of which can cause damage or collapse.
- Saturated Backfill
If backfilled soil is not compacted properly or does not drain for any reason, it can become heavily saturated. This is dangerous because of the extra weight, of course, but poses alternative risks, too. For example, homes in colder climates may find their retaining wills damaged by frost heave if a cold snap hits saturated backfill hard.
- Unanticipated Loads
A retaining wall is designed to withstand a certain load and while the architect will ensure that a certain level of excess is allowed for, they do have a weight threshold. If you buy a property with retaining walls that hold flower beds or patios, for example, and you add a swimming pool, the sudden addition of this heavy structure could cause your retaining wall to fail.
There are, of course, many other things that can damage your retaining walls, including extreme weather and natural phenomena such as earthquakes.
Signs of Retaining Wall Failure
Signs of failure and damage in a retaining wall are usually fairly easy to spot, partly because the wall itself is so exposed and visible. The most important thing to know, however, is that these symptoms are only going to get worse over time. Like foundation problems, structural issues in a retaining wall will not solve themselves. Instead, they will continue to spread, often at an exponential rate, until they are repaired or the wall collapses. The most common signs of a failing wall are:
Spreading cracks are a sign of damage in any wall, but they can be of particular concern in a retaining wall because they have few, if any, other structures to rely on for support. Cracks will most commonly start in the mortar between bricks or stones because these are the weakest points in the wall. Small cracks are not too concerning if they are stable, meaning that they do not spread, but large cracks or cracks that spread over time warrant investigation.
- Leaning or Bowing
Leaning or bowing walls are an obvious sign of instability in any space. As with foundation and basement walls, bowing in a retaining wall is most often caused by excessive lateral pressure as a result of weight, soil expansion, frost heave, or strong hydrostatic pressure.
If your retaining wall is beginning to separate from any structures that it is attached to, this is a strong sign that it is failing. It is also imminently dangerous so you should contact a repair specialist as soon as possible.
If you see any of these signs you should contact a foundation and structural repair specialist as soon as you can. While the damage may not look huge, retaining walls are far more disposed to total collapse than walls within your home. If they do, they can be incredibly dangerous to your property and your person.
Retaining Wall Repair Options
Retaining wall repair is a very specialized and dangerous process; there is no circumstance in which you should try to fix this issue alone. Consider this kind of damage as being similar to foundation damage and seek professional help with the same urgency.
Here at Innovative Basement Authority, we have the skills, experience, and tools to properly address retaining wall failure. We recommend the installation of wall anchors in most cases because they are the most economical and effective solution for this kind of damage. These come in two forms:
- General Wall Anchors
General wall anchors are more cost-effective than helical anchors, but they do require a certain amount of space for installation and are incompatible with certain kinds of soil. Excessively rocky soil, for example, may not be conducive to wall anchor installation.
- Helical Anchors
Helical anchors, sometimes called helical tie backs, are deployed in situations where there is no space for generic wall anchors or where the soil is too rocky. Unlike general anchors, helical tie backs do not require an augur to be drilled in the soil beyond the wall.
Installation of either anchor requires heavy excavation and specialist tools. We do not recommend that you try to install them alone. If you do attempt structural repairs alone, you should at least consult with a professional beforehand to ensure that you are as prepared as possible. Safety should always be your top priority.
Failing Retaining Walls
If you have retaining walls on your property that seem to be leaning or bowing, there are several potential causes to consider. The main thing to keep in mind, however, is that the walls are most likely to collapse if you do not have them repaired, regardless of the cause of the damage. Nonetheless, the most common causes of damage to retaining walls are:
- Hydrostatic Pressure
Hydrostatic pressure, or lateral pressure of any kind, is one of the most common causes of bowing or leaning in an otherwise sturdily built retaining wall. Every retaining wall is built to withstand a certain level of pressure or weight, but many things can cause the level of pressure being exerted to tip over that threshold.
Underground water sources and saturated backfill soil, for example, can cause the weight of the soil behind the retaining wall to exceed its load-bearing capability. If this doesn’t happen, however, the hydrostatic pressure could be compounded by the expansive force of that water as it freezes in winter. Finally, if there are no weep holes to allow water to escape the soil behind a retaining wall, damage and failure are likely.
- Poor Design or Construction
Another common cause of retaining wall failure is a miscalculation in the likely weight and pressure it will face at the design stage. For example, if the architect fails to account for the expansive force of soil when it is wet, the weight of water during rainfall, or the number of supports required to keep the wall straight and sturdy, the wall will quickly begin to lean.
Likewise, if the contractors building the wall fail to install the correct number of supports or they place supports incorrectly, the wall may be unable to withstand predicted loads and pressures. Likewise, if the materials used to build the wall are substandard or damaged at the time of construction, it is likely that the wall will begin to fail.
The signs of damage in a retaining wall are much the same as signs of damage in any wall in your home. This is because they are subject to the same pressures and forces. Of course, external retaining walls are far more exposed than your property walls and they often stand alone, which makes otherwise small signs of damage even more concerning. The most pressing signs of damage are:
- Bulging or Bowing
Bulging, leaning, and bowing within a retaining wall are, of course, incredibly worrying signs of structural damage and instability. Caused by an excess of lateral pressure on the wall, leaning, bulging, and bowing are different variations of the same problem. The area of the wall which shows the most obvious signs of deviation is likely the weakest.
In these cases, you must seek to stabilize and repair the wall as quickly as possible. Any kind of unevenness in a retaining wall is likely to develop with alarming speed and could reasonably end in a large section of the wall collapsing entirely. If this happens, the wall may need to be completely replaced (which is both a costly and lengthy process).
- Stair-Step Cracking
Stair-step cracking refers to wide or spreading cracks that move through the mortar between bricks or concrete blocks. Cracks begin here because it is the weakest point of a wall, but once the mortar has begun to crack it weakens the structure as a whole. One of the most common causes of stair-step cracking is an excess of lateral pressure, but there are others.
Another common and destructive cause of cracking is tree root invasion. If you have bushes or trees in and around your yard their powerful roots can spread and put pressure on any retaining walls in their way. If you are lucky the roots will pass under the wall, but if they press against the retaining wall, they can cause cracks and even gaps to open up.
If you have retaining walls on your property that are showing signs of damage, you have several potential solutions at your disposal. Of course, there is always the option of removing and rebuilding the wall entirely, but this is a costly and time-consuming process that may not be necessary. The most common and effective solutions are wall anchors, but of course, you will need professional help to decide what the safest choice is.
- Call a Professional
First, we do not recommend that you attempt a DIY solution to this issue. There are many reasons as to why this is a bad idea but the most pressing come under two headings: capability and safety. Structural repairs require specialist tools and skills to ensure a safe and complete repair process. If you try to fix this alone, you run the risk of making the issue worse in the long run.
Furthermore, many people don’t realize that repairing a damaged retaining wall (especially one which is leaning or bowing) is in and of itself a dangerous process. Wall anchor installation, for example, requires excavation and drilling; if you don’t place the anchors correctly or you drill in the wrong place the wall could collapse onto you.
- Install Wall Anchors
Once you have a professional in your corner, you should consider whether wall anchors are the right choice for you. Your contractor will be able to assess the situation and advise you as to whether general anchors or helical anchors are right for you. If you have excessively rocky soil or little space behind your retaining wall, helical anchors are likely to be the best choice.
There is a small chance that carbon fiber reinforcement may be the right solution for your retaining wall, but this is highly unlikely. First and foremost, this is only suitable for walls that have deviated by less than 2 inches. It also relies on a smooth surface for proper adhesion. If your contractor recommends it, however, it would be sensible to consider it.
Choose Innovative Basement Authority for Your Retaining Wall Repair
If you have a retaining wall on your property that is showing signs of damage and failure, don’t put off repairs as this could affect the safety of your home and your family. Trust in the local experts at Innovative Basement Authority for professional guidance. Once you contact us for a free inspection and repair estimate, one of our highly trained professionals will be able to examine your retaining wall and foundation and recommend the best course of action for repair.
We will provide you with a same-day, written estimate which details all required work and associated costs. This means that you can take your time and make an informed decision, safe in the knowledge that you have a good idea of the costs and timescales required to restore your retaining wall to its original state.