Causes of Foundation Failure

While some are more common than others, especially as it relates to Oklahoma, there is no one single cause for foundation failure. Different types of foundations have different problems unique to them, and even then there are often multiple causes. Let's look at some of the most common, which foundations they effect and why they cause foundation failure.

Foundation Settlement

What is it?: This is the big one. Foundation settlement is when your home's foundation, or portions of it, settle or sink. This is a general category. Some of the specific causes of the settlement will be discussed later.

What foundations does it affect?: Settlement can affect any type of foundation, it just might take slightly different forms. In slab or basement foundations, it is the foundation slab that starts to settle. With crawl space foundations with a stem wall, it is the stem wall that begins to settle. With pier and beam foundations, one or more of the individual piers supporting the beams could start to settle.

Why can it cause foundation failure?: Almost all homes settle slightly initially. This can cause some hairline, usually vertical wall cracks, but if it stops there, it won't result in foundation failure. But larger amounts of settlement, especially differential settlement in which different parts of the foundation settle different amounts, is a significant problem.

In the case of differential settlement, the issue comes from the fact that some parts of the foundation are receiving the proper amount of support while others aren't. Eventually, the stress from this is going to do two things. First, it is likely to cause cracking in the walls, foundation slab or even ceiling. Second, it will make the entire house shift out of alignment. This will make doors and windows stick and/or have gaps because shifting makes it so they no longer properly fit in their frames.

How do you fix it?: For all except pier and beam, the answer is generally foundation underpinning. This means installing piers that extend deeper into the soil to transfer the load of the home off of the unstable soil directly below the home and onto the piers and the more stable soil farther beneath the surface. For pier and beam foundations, piers may have to be stabilized or replaced with ones less prone to settling.

Erosion

What is it?: Erosion is the loss of soil because of the effects of other forces, usually wind or water.

What foundations does it affect?: Erosion can impact any foundation because erosion around or beneath the foundation can affect the level of support the foundation is receiving from the soil below.

Why can it cause foundation failure?: Erosion is one of the more specific causes of foundation settlement. If erosion weakens the soil around a foundation, that foundation then becomes more prone to settlement.

How do you fix it?: Because the problem is generally under the settlement grouping, the answer is generally foundation underpinning. If the erosion was caused by water, it might be advisable to also implement exterior drainage options like French drains to safely divert water to places less likely to erode the soil around your foundation.

Improperly Compacted Soil

What is it?: Before construction begins, the soil beneath a foundation should be compacted. This is a process of stabilizing the soil by mechanically compacting it to remove any looseness or voids in the soil before the home is built. If this isn't done, or isn't done properly, it increases the risk of settlement.

What foundations does it affect?: Much like erosion, improper soil compaction can impact any foundation because settlement can affect any foundation.

Why can it cause foundation failure?: Improper soil compaction is another of the more specific causes of foundation settlement. If the soil or loose or has voids before construction, the weight of the house will likely cause it to settle, leading to foundation problems.

How do you fix it?: Ideally this wouldn't be an issue because it would be fixed before construction begins. If it isn't, however, the solution is again usually the installation of a foundation underpinning system.

Wood Rot

What is it?: Wood that is under exposure to too much moisture can begin to rot, degrading the strength that it provides.

What foundations does it affect?: Although some of the basement structures supporting the floor above could rot, this is mostly an issue in the two kinds of foundations that have crawl spaces: stem wall and pier and beam.

Why can it cause foundation failure?: Most foundation failure stems from portions of the foundation not being properly supported. When the beams or floor joists in a crawl space rot, it weakens them. This means that they may begin to sag and cause other foundation problems.

How do you fix it?: If the wood rot is contained, adding an additional pier to support the weakened beam can sometimes work. In general, though, the affected beams or joists will need to be replaced. Waterproofing measures such as crawl space encapsulation should also be considered to ensure the problem doesn't come back in the future.

Hydrostatic Pressure

What is it?: The pressure exerted by excess water in the soil.

What foundations does it affect?: Any foundation with below grade (below the surface) walls. This is primarily basement and stem wall foundations.

Why can it cause foundation failure?: Water accumulating around foundations can push inward on the foundation walls. This can cause them to crack and bow and ultimately could cause them to give way.

How do you fix it?: There are a variety of options available to fix the wall itself. One portion of the fix, however, should be an exterior drainage system to prevent the water from pooling around your foundation walls to begin with.

Active Soils

What is it?: Clay and other similar soils have a significant shrink/swell cycle depending on the moisture level. As it gets wet, it significantly swells and then shrinks down as it dries out.

What foundations does it affect?: It can affect any foundation, but those with a lot of area exposed to the soil are most at risk. Slab foundations can settle or heave. The swell portions of the shrink/swell cycle can cause the soil to push inward on basement or stem walls, similar to the hydrostatic pressure described above. Pier and beam foundations might be less affected, but it still could throw a pier out of alignment, necessitating it be fixed or replaced.

Why can it cause foundation failure?: If it is the shrink part of the cycle that is causing the problems, settlement can occur. If the soil swells instead, heaving can occur, which can cause basically the same problems as settlement but for the opposite reasons. Instead of one part of the foundation sinking as in settlement, it gets pushed upward. This leads to the same pressure and lack of alignment that causes issues with settlement.

How do you fix it?: Exterior drainage can help keep the soil around the foundation dryer, limiting the effects a bit. As with settlement, underpinning systems are also often advisable as they are anchored in a more stable strata of soil.

Pier Degradation

What is it?: When a foundation pier is damaged, weakening the support it is able to provide.

What foundations does it affect?: Pier and beam.

Why can it cause foundation failure?: If the pier is weakened, it can't provide the correct amount of support to the beam above it, leading to sagging and foundation problems.

How do you fix it?: Either repair (if minor issue) or replace the affected pier or piers.

Suspect Your Oklahoma Home's Foundation is Failing? Contact Us Today

If you have foundation settlement in your Oklahoma home, don't hesitate to call Pierman Foundation Repair Services today. We can provide you with a free quote for any of your foundation repair needs or exterior drainage needs.