Foundation collapse, repair (C) Daniel FriedmanExpansive Clay Soil Damage to Foundations
The Main Causes of Buckled Foundation Damage in Wet, Freezing Climates with Clay Soils

  • FOUNDATION FAILURES in CLAY SOIL - CONTENTS: Main Cause of Foundation Failures in Clay Soils. Roles of water, frost, clay soils, and insulation in foundation damage cases Where and with what material can we insulate building foundation walls?How Avoid Foundation Cave-Ins How do we prevent foundation damage - key steps. Solar Age Magazine Articles on Renewable Energy, Energy Savings, Construction Practices
  • POST a QUESTION or READ FAQs about the causes of buckled building foundations for structures built in wet freezing climates and or on clay soils
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Expansive clay soil damage to building foundations or slabs:

Role of frost, freezing, & clay or wet soils in foundation heaves, cracks, damage: this article explains the main causes of foundation cracks, buckling, or collapse in areas of freezing weather, clay soils, or wet soils.

We provide suggestions for avoiding foundation damage or collapse and we discuss the proper foundation insulation locations and materials for use in problem areas. Photo (above) shows a new foundation constructed below a New York home after a catastrophic foundation collapse caused by wet soils.

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What is the Main Cause of Foundation Failures in Expansive Clay Soils?

Buckled building foundation (C) InspectAPedia.comThe USGS defines "expansive soils" as

Types of soil that shrink or swell as the moisture content decreases or increases. Structures built on these soils may experience shifting, cracking, and breaking damage as soils shrink and subside or expand.

The following includes text adapted from Solar Age Magazine, Steven Bliss: Most foundation failures in clay soil have nothing to do with freezing. The culprit is more often the expansion of the soil when it absorbs water.

In Fargo, said housing engineer Lambert Vogel, when the soil dries out and shrinks, it can pull away from the foundation as much as two inches to a depth of three feet or more.

Either the wind or the homeowner is likely to fill this crack with loose soil. When the clay soil gets wet again and expands, crack goes the wall - if it is weak.

In some areas of expansive clay soils such as portions of Colorado, builders install a soil watering system below the building's foundation and slab in order to prevent this clay soil shrinkage during dry weather.

Watch out: other more varigated concrete crack patterns (shown below) may be ascribed to FOUNDATION DAMAGE by MATERIAL or INCLUSIONS producing soil heaving, unstable soils, or crack patterns in concrete caused by inclusion of iron sulfide (pyrrhotite) particles in the concrete mix itself.

Recommendations to Avoid Foundation Wall Cave-Ins in Cold Climates

Vary rarely do foundation walls cave in from insulation, except possibly in Duluth, Minnesota, where all the conditions are ripe for foundation failure: lots of rainfall, clay soils, very cold winters, and building practices that often do not include foundation drainage to assure that soils close to the building foundation are not water-saturated.

But you can prevent all frost-related foundation damage problems by following standard good building practices:

Given basically sound foundation and site work, it is acceptable to insulate a building foundation inside (giving up the thermal mass benefits to the building) or outside, and to install foundation wall insulation half-way, full-height, or flared-out - anywhere in the continental United States.

In foundation insulation retrofits in very cold climates, life is not so simple. What if you have an un reinforced concrete block foundation, a frost-susceptible soil (clay or silt), and poor site drainage? Then we would be reluctant to install any foundation insulation without first correcting the site - at the very least by conducting surface water and roof spillage well away from the building foundation.

Where the integrity of the foundation wall is in doubt, there are compromise solutions. We might install half-height insulation on the inside of the foundation wall, or half-height insulation n the outside of the foundation wall with the addition of at 2- to 4-foot flare.

But don't expect good thermal performance with half-height interior foundation insulation on an open-core concrete block foundation wall. Convection in the concrete block cores will carry heat right past the insulation.

Also consider the wintertime temperatures in the basement or crawl space. If the building owners have insulated the basement or crawl space ceiling, and are heating with a woodstove upstairs rather than a furnace or boiler in the basement, the basement walls, not to mention the water pipes could get very cold.


Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

Useful Research on Expansive Soil Damage Assessment


Continue reading at FROST HEAVES, FOUNDATION, SLAB or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.




Or see FOUNDATION FAILIURE by INSULATION - insulation causing foundation buckling or damage


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