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Foundation Settlement 101: Why and How Foundations Fail

Jan 22, 2019 | Foundation Repair, Residential, Structural Engineering

Whether you’ve lived in your home for many years or you are preparing to purchase a property, it is important to understand that the safety and longevity of your structure are dependent on a healthy foundation. The foundation’s job is pretty simple. A proper foundation will support the weight of the structure and transfer the load to below grade. When a foundation fails, however, many elements of the structure could be compromised.

A good foundation relies on two strengths. The first is the strength of the foundation itself. The second is the strength of the soil that the foundation is built upon. Both are important to the health of the structure, but one is easier to control. The strength of the foundation itself requires good materials and proper design. These elements can be controlled during design and construction and they are regulated by building codes. This is why most recently built structures have strong foundations. The condition of the soil under the foundation is more difficult to account for, which is why foundation problems are commonly linked to settlement problems.

Here are four common causes of foundation settlement:

Poor Ground Preparation Prior to Building

Poor ground preparation can cause foundations to failThis is a problem of improper construction methods. Contractors often use fill soil to prepare a site. If the fill soil has not been compacted properly before foundation construction, it will not adequately support the weight of the structure and the foundation may settle over time.

Poor Soil Composition

soil composition effects foundation settlementIdeally, it would be great to know the underlying soils are strong enough to support a structure before it is built upon. Geotechnical engineers can use their expertise and soil testing to determine if a site is adequate for building. A Geotechnical engineer can advise an owner if foundations should be underpinned with pilings to bear on stronger, deeper soils. 

Poor Drainage

poor drainage can cause foundation settlementPoor drainage is a common problem, especially in wet climates like the Pacific Northwest. Even good soil can erode over time due to changes in moisture content. Good site preparation and monitoring is key. If poor drainage is a problem, a civil engineer can evaluate your site and create a plan to direct water away from your home.

Plumbing Leaks

Structural engineers can repair foundationsSometimes, water in the soil near a foundation can be traced back to plumbing and irrigation leaks near the home. Fixing the leak will help the situation, but if the foundation has already settled it may still need to be evaluated by a professional engineer.

Compromised Foundation Structure

If the foundation was not built to code, is compromised, made of inferior materials, or the home is historic, there could be problems with the foundation itself. Although this is less common than the other foundation problems, it is one reason that foundation problems should be assessed by a licensed structural engineer. No matter what the cause, problems with the foundation can compromise the structure.

It is important to not only fix the foundation, but to determine the cause of the foundation settlement before taking action to repair it. Quick fix foundation repairs are not a good solution to foundation problems.

If you are worried about your foundation, we recommend that your first course of action should be to call a structural engineer that is licensed in your state and has experience evaluating and repairing foundations. A structural engineer will provide an unbiased, professional assessment of the structure and help you identify the next steps you should take to safely repair it. Educate yourself on the signs of foundation settlement, why you need a structural engineer for your foundation repair and learn about types of foundation repairs before you engage a contractor, so you can make an educated decision that will protect the value of your home.   

CG Engineering can provide a level survey of your home that shows where and how much settlement has occurred and recommend foundation stabilization techniques for repair.

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If you have questions about your foundation repair project, please contact us and one of our engineers will help you answer them.