The Role Of A Foundation
Your home’s foundation is the lowest part of the structure and uniformly transfers the building’s Structural load to the soil. The foundation keeps your home above ground, and makes sure it won’t end up like the Leaning Tower of Pisa. It also insulates the structure against cold, keeps moisture out, and prevents the building from shifting in response to soil movement. Without a sound foundation, your home will eventually develop serious structural problems.
Ensuring a sound foundation means properly preparing the soil before construction begins, and doing what needs to be done in order to ensure the foundation doesn’t develop problems later. We’ll talk more about this in a bit. Just know that the structural integrity of your home is only as good as the soundness of its foundation.
What Causes Foundation Problems?Most foundation problems are caused by water, either too much or too little. Homes built on top of expansive soil – that is, soil with a lot of clay in it that swells when it soaks up moisture, and shrinks when it dries out – can develop structural problems because the repeated swelling and shrinking of the soil creates movement under the foundation. Because this movement isn’t uniform, it causes what’s referred to as “differential settlement”. Differential settlement can cause serious structural damage.
Homes built atop sandy soil are also susceptible to problems when there’s a lot of water under and around the foundation. This is because soil with a lot of sand in it easily erodes, and when this happens it creates voids under the foundation which lead to instability.
Of course, this doesn’t mean that foundations built atop other types of soil are immune to problems caused by excess water, only that foundations built atop soils with a lot of clay and sand in them are especially susceptible to problems related to water.
Foundation problems are also caused by…
- Soil that hasn’t been properly compacted prior to construction – Soil that has been disturbed, or soil used for fill must be compacted before the foundation is built on top of it. If this isn’t done, there will be settlement.
- Drainage problems – This can lead to too much water under and around the foundation, which can then cause problems, including differential settlement.
- Extreme seasonal temperature variations – One way this can happen is through frost heave in climates with periods of extreme cold. Climates that fluctuate between very wet and very dry seasons can also cause problems if there’s expansive soil under the foundation because the repeated swelling and shrinking causes movement.
- Invasive tree roots – Tree roots can soak up moisture and if you have expansive soil, it will shrink as it dries out. This causes movement under the foundation. Trees should always be planted at some distance from your home.
- A plumbing leak under the foundation – This will, of course, increase the moisture content of the soil under the foundation. If that soil is expansive, it will swell, causing the foundation to move. If it’s a sandy soil, a plumbing leak could lead to erosion.
- Natural disasters such as earthquakes, droughts, and floods – While we probably don’t need to explain how earthquakes cause foundation damage, the damage caused by droughts and floods is probably less obvious. Droughts will cause expansive soil under a foundation to shrink, while even slowly moving flood water can cause walls to separate from a foundation.
How Does Weather Affect My Home’s Foundation?
Weather can definitely affect your home’s foundation. Here are a few ways this can happen…
- If you live in an area with expansive soil where the weather fluctuates between a rainy season and a dry season, the soil will expand during the rainy season and shrink during the dry season. This creates movement under the foundation that will, over time, cause damage.
- If you live in an area with sandy soil where it rains a lot, you’ll need to watch out for erosion.
- Foundations built in cold climates are susceptible to something called frost heave. This happens when the soil under the foundation freezes and expands. This creates movement in the soil that will lead to instability.
- If the foundation has any existing cracks, a cold winter could make them even worse. This happens because water expands as much as 9% when it freezes. If it gets in between the cracks and freezes, it will enlarge them.
This is, of course, not an exhaustive list of the ways weather can affect a foundation.
How Does Soil Affect My Home’s Foundation?
Expansive soils are clay soils that swell when they absorb water and shrink when they dry out. This change in volume is soil movement that puts pressure on a foundation and can lead to structural damage. A soil analysis should always be done prior to beginning any construction project to identify the type of soil, and if it has any expansive properties. For more information, see How Expansive Soils Affect Buildings, published by the American Society of Civil Engineers.
Building on top of sandy soil involves a different set of challenges. For example, sandy soils easily erode and don’t have the ability to support a heavy structure. Therefore, homes built on sandy soil need a deep foundation system.
The best soil for construction is loam (a combination of sand, silt, and clay). It’s easy to compact and doesn’t go through a swell-shrink cycle like clay soil does or erode like sandy soil will.
How Do Trees Affect My Home’s Foundation?
While trees can help prevent soil erosion under your foundation, they can also cause significant damage in the following ways…
- Tree roots can damage a foundation by soaking up moisture in the soil. This causes the soil to dry out and shrink, which can lead to instability.
- Tree roots can physically push against a foundation.
- Tree roots themselves expand when they absorb water and shrink as they dry out. This causes soil movement.
- If a tree dies, it’s roots will decay and shrink. This can also cause soil movement.
How Does Water Affect My Home’s Foundation?
Foundations built atop expansive soil (that is, soil with a lot of clay in it) are especially susceptible to damage caused by water. This is because expansive soil swells – often considerably – as it absorbs water and then shrinks by that same amount as it dries out. This back and forth, swelling and shrinking, causes movement in the soil under the foundation. This will result in structural damage.
Foundations built stop sandy soil are susceptible to damage caused by soil erosion, especially if there are drainage problems. If this isn’t fixed, it could lead to differential settlement and structural damage.
Another way water can affect a foundation is via flooding. Even slow moving floodwater has the ability to seriously damage a foundation. In fact, it can even move the foundation itself. Flood water can also get into small cracks and make them bigger.
Gutter and downspouts
If your gutters and downspouts aren’t in proper working order, rainwater could pool near your foundation and soak into the soil. If this goes on for long enough it could cause settlement. A plumbing leak under the foundation can also cause this.
Gutters and downspouts should dump water at least 10 feet from your foundation.
Understanding hydrostatic pressure
Hydrostatic pressure is another way water can affect your home’s foundation. When the soil around your home’s foundation gets saturated with water, this creates pressure that will push against the foundation. Hydrostatic pressure is the usual culprit behind wet basements. Hydrostatic pressure will not only increase the size of any existing foundation cracks, it can even cause them.
Water should always drain away from a foundation. If you have slope problems, your yard might need regrading in order to divert water away from the foundation. French drains are another method used to make sure water drains away from a foundation.
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Foundation Problems Caused By Improperly Compacted Soil
Foundation problems can also be caused by poor construction practices. In this case, soil that wasn’t properly compacted prior to construction. Compaction is essential for soil that has been disturbed.
The soil under a foundation needs to be very strong, and compaction works to make the soil more dense. If the soil under a foundation has been properly compacted, there shouldn’t be any settlement after the building is constructed. If compaction isn’t done properly prior to construction the foundation will experience different types of foundation settlement, either uniform or differential.
Soil is compacted in a variety of ways, and the chosen method depends on the type of soil.
Common Signs Of Foundation Problems
- Windows and doors that don’t open and close properly
- Uneven floors
- Wall cracks that start at the corners of doors and windows, and then go up toward the ceiling. If these are hairline cracks, it might not be anything to worry about.
- Bowed walls
- Cracks in floors that run from wall to wall. If the crack is limited to one tile, it’s usually nothing to worry about. Perhaps something fell on the tile and cracked it.
- A sagging floor that feels spongy when you walk on it
- A damp basement or crawl space. This could indicate there’s too much moisture in the soil around the foundation.
- Any large horizontal or vertical cracks
- Bowed walls
- Rotated walls. This happens when the soil around the foundation is over saturated with water. The outside edge of the foundation sinks into the wet soil while the dry, inside edge pulls up. As a result, the wall rotates.
- Any large horizontal or vertical cracks
- Stairstep cracks in brick or masonry
- A leaning chimney or porch
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Which Cracks Are Serious And Which Aren’t?
While most cracks are caused by foundation movement, their presence doesn’t necessarily mean you have structural damage. In other words, your foundation can move slightly for some reason and cause a crack. However, this doesn’t necessarily mean you have foundation damage. Homeowners need to be able to spot cracks that indicate possible damage to their foundation. So, be on the lookout for…
- Wall cracks that go down a wall and then across a ceiling or floor
- Any large horizontal or vertical wall cracks that span the length or height of the wall
- Bowed walls
- Stairstep cracks in brick or masonry
- Moldings that are cracked and/or out of place
- Wall cracks that run from the corner of a door or window up toward the ceiling. If these are hairline cracks, they probably aren’t anything to worry about.
- Gaps between the wall and the ceiling and/or the floor
- Spiderweb cracks that radiate from a central point. If these are hairline cracks, they probably haven’t been caused by foundation damage.
Hairline cracks usually aren’t a sign of structural damage. Larger cracks – in both length and width – are more likely to indicate structural damage. However, there are always exceptions. If you have a suspicious crack, contact a foundation repair professional for an inspection.
For more information about ceiling cracks, see our article Are Ceiling Cracks Serious? Causes Of Ceiling Cracks And When To Worry.
Residential Foundation Repairs: Methods
Sometimes a home’s foundation is no longer able to support the structure. This could happen for a variety of reasons including,
- The soil under the foundation has eroded, compacted, or been affected by the cyclical swelling/shrinking cycle expansive soils go through as a result of seasonal changes.
- Poor construction. Sometimes builders don’t take into account the type of soil the foundation is sitting on.
- A natural disaster such as an earthquake or flood has damaged the foundation.
- Nearby excavation has destabilized the foundation.
Foundations that are no longer capable of supporting the structures that sit on top of them, can be repaired via a procedure called underpinning. Underpinning strengthens and stabilizes the foundation so that it’s once again able to support the structure.
Most residential foundation repairs involve using push piers, helical piers, drilled concrete piers, or slab piers to stabilize the home’s foundation.
Push piers (Also known as resistance piers)
When a foundation is repaired using push piers, steel brackets are first attached to the bottom of the foundation. Once they’re in place, a steel pier is driven through each bracket until it reaches load-bearing soil. A hydraulic lifting system then lifts and levels the foundation.
Helical piers are shaped like giant screws. They’re screwed into the soil under the foundation until they hit the load-bearing strata. After they’re in place, the house is lifted and leveled using a synchronized hydraulic system.
Note: While push piers are only used for repairing foundations, helical piers are used both for repairs and for new construction projects requiring a deep foundation system.
Drilled concrete piers
Homes built on the sides of hills can experience settlement and lateral movement due to a phenomenon called soil creep. In simple terms, this means that soil at the top of the hill will, because of gravity, eventually end up at the bottom of the hill.
Drilled concrete piers are used to stabilize the foundation and resist lateral movement. The installation procedure involves drilling holes – around 18 inches in diameter, and from 15-30 feet deep – next to the foundation. Reinforcement cages are then place into the holes, and then the holes are filled with concrete. These are known as cast-in-place drilled concrete piers.
Slab piers (either push piers or helical piers)
Slab piers can be either push piers or helical piers. They are installed via drilling small holes in the slab. Anchors are then driven through the holes and down to load-bearing soil. Steel brackets are used to secure the anchors to the foundation.
Screw jack replacement
Sometimes a home will have signs of settlement even though there’s nothing wrong with the foundation. This usually happens when there’s a problem with the crawl space. Either the support posts have settled, or the screw jacks have deteriorated. Signs of this include a floor that feels spongy, or furniture that shakes when you walk by.
This problem can often be solved by using the existing pier blocks and then replacing the posts or screw jacks. The floor can then be lifted and leveled.
Will My Homeowner’s Insurance Cover Residential Foundation Repairs?
Maybe. It depends on what caused the damage. If the foundation was damaged by a covered problem, the insurance will undoubtedly take care of it. In other words, if you have earthquake insurance and the foundation damage was caused by an earthquake, you’re probably covered.
If the foundation damage was caused by age or normal wear and tear, probably not. Of course, the only way to know for sure is to call your insurance agent and ask.
How Much Do Residential Foundation Repairs Cost?
That’s hard to say. The cost of a foundation repair will depend on where you live, the foundation type, the problem, the severity, and the type of repair needed. Contact a foundation repair professional for an inspection and estimate.
You can also contact a structural engineer for an inspection. That person will write up a report detailing the problem and how it should be repaired. You can then give that report to the repair contractor.
Major foundation repairs are costly. That’s why all homeowners should learn to spot foundation issues early, before they have a chance to turn into major problems requiring an expensive repair.
How To Prevent Foundation Problems
Residential foundation repairs can be expensive. Therefore, you’ll want to make sure you catch problems early. Assuming your home’s foundation has been properly constructed, and given the fact that most foundation problems are caused by either too much or too little water, you should…
- Ensure that the soil around and under your home’s foundation never becomes too wet or too dry. This means – among other things – making sure your property is graded so that water flows away from your foundation. It also means making sure gutters and downspouts are free from debris and don’t deposit water near your foundation.
- Keep trees and shrubs away from the foundation. Large tree roots can soak up moisture and dry out the soil, which can cause a foundation to destabilize.
- Do whatever needs to be done in order to keep water from pooling around the foundation. For example, you might need to regrade your yard or install a French drain.
- During droughts, water the soil around your foundation so that it doesn’t dry out.
What Should I Do If I Suspect My Foundation Has A Problem?
If you think your home might have a foundation problem, contact an experienced contractor that does residential foundation repairs for an inspection and estimate.
Alternatively, you could contact a structural engineer who will perform an inspection and then write up a report detailing the problem and the repair solution. You can then take that report to the foundation repair contractor.
Selling A Home With A Foundation Problem
It is possible to sell a home that has a foundation problem. However, you are legally required to disclose the problem to all potential buyers, in writing.
If your home has a foundation problem and you want to sell it, you have two options:
1. Fix it first, and then sell it.
2. Sell it ‘’as is’’ to an investment buyer.
For more detailed information about selling a home with foundation problems see How To Sell A House With Foundation Problems.
How To Hire A Contractor For Residential Foundation Repairs
If your home has a foundation problem, you need to first of all educate yourself about the various ways foundations are repaired. When you talk to the repair contractor, ask a lot of questions. The contractor should be very willing to answer any and all questions related to work that’s going to be done on your home’s foundation.
The contractor’s repairs should be evaluated by ICC-ES (International Code Council Evaluation Services) to make sure they’re up to code, and the contractor should offer you a warranty. Keep in mind though that the warranty is only as good as the company behind it.
Your home’s structural integrity rests – literally – on the soundness of its foundation. You can prevent damage to your home’s foundation by…
- Keeping up with maintenance
- Keeping an eye out for cracks, leaks, or any other signs of structural damage
- Making sure the soil around your foundation isn’t too wet or too dry
- Making sure gutters deposit water away from the foundation
- Planting any new trees away from the foundation
- Making sure you have insurance that will cover as many foundation problems as possible
If you need help with a residential foundation repair and you live within one of our service areas, contact us today for free estimate.