Foundation Soils

The soil underneath and around your property may not cross your mind very often, but the ground that your home rests on could be the most important part of the whole structure. It is the most important part of your property for one very simple reason; the soil under your home makes the difference between foundational stability and a world of problems. At its most basic level, this is all to do with the makeup of the soil in the area and how it behaves in response to climatic changes. Different kinds of soil are more likely to shift, expand, contract, or erode, depending on the weather and temperature.   

There’s little an architect, contractor, or even a foundation repair specialist like Innovative Basement Authority can do to change the soil under your home. What we can do is provide solutions that help your property to stand strong no matter what the world throws at it.    

Different Soil Types: What You Need to Know    

While there are thousands of different possible soil combinations – which are categorized depending on their fertility, mineral content, and the amount of rocks and other debris they contain – there are only three kinds that you need to be aware of: sandy soils, clay-based soils, and sandy loam soils. Each of these soil mixes reacts differently to water.   

• Sandy Soils   

Sandy soils are the most stable of soils because water passes through them rather than being absorbed. This means that their volume is pretty stable regardless of the weather conditions or relative humidity, and when they are well compacted, they have remarkably high load-bearing capabilities. However, when sandy soils are loose or poorly compacted, they can be prone to erosion or shifting – this is very uncommon, however, and sandy soils remain the best for building upon (which is a shame because they are rare).   

• Clay-Based Soils   

Clay-based soils technically include those which are rich in silt or peat, too. These soils are the most likely to cause damage to a property’s foundation. This is because of how they capture and hold moisture. Clay soils are very expansive and can grow or shrink quite dramatically as a result of saturation or dehydration. They can also heave dramatically in cold weather when they are saturated; these soils are more likely to cause damage by expanding than shrinking (but both movements are capable of causing damage).   

• Sandy Loam Soils   

Sandy loam soils are the most common across North and South Dakota, as well as Minnesota and they are fairly stable; while they can expand slightly with saturation or snap freezes, they are unlikely to cause damage as a result of this. Sandy loam is far more likely to erode than its primarily sandy counterpart, however, making it less stable than sandy soil and more prone to causing issues like settlement.   

Each of these soils can be found in varying forms across most of the continental U.S., but loam-based soils are the most common in Minnesota, North Dakota, and South Dakota, with some sandier soils on outwash plains and stream terraces. These areas provide fairly stable soil for construction, but there are some places that are less stable than others. This is why a soil analysis can be so useful. Just because a certain soil mix is predominant in your area doesn’t guarantee that your property is resting on the same kind of earth. Soil changes can be surprisingly localized, especially if you are near a river or lake.   

The “Active” Zone    

The soil under your home is made up of many layers, and each has a specific thickness and characteristics. Lower levels of soil are more stable and densely compacted than layers closer to the surface. Far below these layers, there is also a layer of bedrock that is composed either of rock or solidly compacted soils.   

While all these layers of sand, loam, clay, and rock have an impact upon your property the layer you should be most concerned with is the one known as the ‘active zone’. The active zone is the soil that is immediately under and around your property. This is the soil most affected by changes in temperature and climate. This is also the layer of soil most likely to cause problems for your home. One of the most destructive issues that your home can face is settlement.   

What Causes Settlement/Sinking?   

Settlement occurs when the soil can no longer provide support to your property and foundation. The most common causes of foundation settlement are the shrinking of soil as a result of dehydration, the softening of soil as a result of saturation, and poorly compacted backfill after construction.   

• Dried Out Soil   

Dried out soil can come about in several ways. The most obvious is a drought; prolonged periods of hot, dry weather can cause soil to dry out far below the surface, but they are not the only potential causes of dry soil. Maturing trees can also cause the soil around your home to dry out.   

Trees have huge and powerful roots that far exceed their canopies; if you have a tree that covers or reaches the perimeter of your property then its roots are certain to be under your home. These roots can draw water out of the soil under your foundation and dry it out sufficiently to cause shrinking and settlement.   

• Wet Soil   

There are three main causes of excessive soil saturation: flooding or heavy rain, poor drainage, and man-made floods. Heavy rain and flooding are distinct from man-made flooding which is caused by burst water lines and plumbing leaks. Finally, poor drainage in and around your property can lead to soil saturation very quickly when heavy rainfall hits.   

• Poorly Compacted Backfill   

Once a property has been constructed any voids are filled with soil, either with soil that was removed during excavation, or soil that is brought in specifically to fill these voids. Builders will take the time to compact this soil as well as they can, but newly moved filler soil is much looser than the dense virgin soil. While it may begin to compress over time, it can also shift and create foundation problems.   

Foundation damage can also be caused by a mix of these issues, or by other pressures on your property; these are simply the most common causes of settlement. Depending on the type of soil you have, these same issues could cause subsidence, and if your property is very light you may not experience any issues until a particularly hard winter causes foundation heave.  

Foundation Soils

FAQs

Why Is My Foundation Damaged/Sinking?

If you are noticing sinking or damage in your property’s foundation, there are a few potential culprits. While soil-based issues are the most common causes of damage to the structure of a home, there are other potential causes. Structural defects in design or construction are uncommon, but not unheard of.  

• Soil-Based Issues 

Soil that is excessively wet or dry can cause foundation issues like subsidence and settlement in your property. This occurs most often when the loose, backfilled soil fails to drain rainwater, forming a “clay bowl” around your home, or when expansive clay-based soils become incredibly dehydrated. If the soil under your foundation is firm, the excess hydrostatic pressure can cause walls to crack, but if the soil under your home is loose or marshy enough, this extra water can render it unable to support your property.   

Settlement, by contrast, tends to happen when expansive or weak soil is dehydrated. Expansive soil will contract sharply, often cracking as it does so, while weak soil can simply begin to wear away. Either way, your foundation can be left without support in some sections. When this happens, your property will begin to sink, usually in an uneven manner, or else its foundation might start to fragment and drop into the voids left behind.   

• Flawed Design or Materials  

Soil-based issues are some of the most common causes of foundation damage and structural movement in the U.S. today, but they are not the only possible causes. Structural defects, either in design or in the materials used during construction, are possible and they can be incredibly destructive. One example of this is a miscalculation in the required depth of a property’s foundation. This kind of miscalculation can easily result in a weak foundation that is unable to bear the weight of the structure that it holds.  

As most foundations are made of concrete, either poured or slabs, any flaws in the concrete itself will result in cracking, fragmentation, and cosmetic damage to a property’s foundation very quickly. One example of this kind of defect is poorly mixed or cured cement. This can lead to an improper distribution of water in the surface and allow fault lines to form in a foundation. This is almost guaranteed to end up causing fragmentation and, over time, settlement or sinking.  

How Can I Deal with Unstable Soil?

Unstable soil is hard to control and rectify, but there are a few things that you can do to mitigate the effects it is having on your property and foundation. First, you can take measures to strengthen its ability to stay together. Secondly, you can take steps to stabilize the amount of moisture in the earth around your home.   

• Stability   

Improving the stability and strength of your soil can be difficult if you are not well-versed in landscaping and gardening. As such, we recommend that you contact a professional to get their insight and advice. It could even be helpful to have a sample of your soil analyzed to show just what is in it.   

Once you understand what you have, you can take measures to improve its ability to deal with stress and stay together in the face of saturation and dehydration. The most effective way to do this is to plant a mixture of flowers, bushes, and trees; the complex root systems formed will not only increase the soil’s capacity to deal with water but will also help it to bind together.   

• Moisture Management   

Managing the amount of water that is in your soil at any given time is another effective way to deal with unstable ground and protect your property. This takes two forms: drainage and hydration. First, you should make sure that you have effective drains, gutters, and downspouts on your property. These should funnel excess water away from your perimeter and out to the street in heavy rain.   

Secondly, having a water-efficient sprinkler system in place to ward off extreme dehydration in the driest months of the year is an excellent idea. While these will no doubt be banned when a severe drought happens, regular water up to this point will minimize the extent of dehydration to some level.   

How Do Pier Systems Work?

There are many options available for pier systems, including slab piers, helical piers, and push piers. These systems all have special unique features, but they also have some features in common overall. Here’s how a pier system works in general.  

• Drilling Down into the Earth  

The first step is the method by which an expert will be able to install the piers. This may vary depending on what type of pier system they are installing. For example, the expert may drill through the foundation concrete or use foundation brackets. Then, the expert will drill steel tubes down until they reach the correct soil layer.  

The correct layer of soil may differ depending on the pier type and the location. Some homes may require that the piers go all the way down to bedrock, while some homes may be able to reach down just a bit and access more stable soils. Either way, an expert will be able to tell when they’re able to stop driving pier sections through the foundation.  

• Lifting Your Foundation 

The next step is to use the pier section to actually lift the concrete foundation. This requires that the expert transfer the weight of the foundation from the current soil it’s sitting on to the deep soil that the pier is sitting on. From there, it’s possible for the expert to attempt a lift, which will bring the foundation back to its original place.  

Once the foundation has been lifted back into place, it  will be stabilized by the piers and can be used like normal. There is no set-up time or process required. Once the piers are in place, they can ensure your foundation is properly supported and safeguarded against future strain. This is best paired with annual maintenance checkups to ensure that none of the problem signs return later on due to other factors.  

Address Your Foundation Soil Issues with Professional Foundation Repairs   

Innovative Basement Authority is a local foundation repair expert with a diverse and skilled team of professionals on hand to help homeowners across Minnesota, North Dakota, South Dakota, and eastern Montana. We have spent a lot of time gaining an understanding of the soils that are most common in these regions and, as a result, have been able to curate a portfolio of effective repair solutions for foundation problems of every kind. From foundation piers to wall anchors, we only invest in products that we know will give our customers the results that they deserve.    

Whether you need us to lift sunken flooring, reinforce and straighten bowing walls, or simply waterproof your basement as a protective measure, you can rest easily in the knowledge that we have a sparkling reputation for excellence. With many years of experience and thousands of jobs under our belt, there is no problem that we can’t tackle. So, don’t hesitate to contact us for a free inspection and repair estimate.