Repairing Foundations Damaged by Expansive Soil
The type of soil that surrounds a building can have a major effect on the building’s foundation. Expansive soil is one of the most problematic soil types in terms of foundation damage; it causes billions of dollars of damage throughout the U.S. every year. Found in many parts of the country, expansive soil has a high clay content. During wet weather, water doesn’t drain through expansive soil like it does through sand and gravel-based soils. Instead, water molecules bind to clay particles in the soil, causing the volume of the soil to increase.
Problems Arise From Soil Expansion and Soil Shrinkage
Expansive soil can exert over 5,000 lbs. of pressure per square foot on a foundation wall. This lateral pressure can cause a foundation wall to crack, bow or tilt inward. When expansive soil is located beneath a slab, it can sometimes cause the slab to crack and heave upward.
Problems can also occur when clay-rich soil dries out. During dry spells, clay-rich soil shrinks away from foundation walls. Gaps between the soil and a foundation wall allow large amounts of water to enter during rainy weather, increasing the soil’s expansive force. Alternately, these gaps are sometimes filled with stone, additional soil and other debris that can also increase lateral pressure against the foundation during the next wet cycle. Another way that soil shrinkage causes damage is by creating voids beneath footings or slabs that cause these masonry elements to crack and settle.
Call in a Foundation Repair Specialist to Solve Expansive Soil Problems
To determine whether or not expansive soil is to blame for specific foundation damage, it’s advisable to call in a foundation repair expert who is familiar with local soil conditions. Since water is what makes clay-rich soil swell and shrink, one of the first things a foundation repair contractor will do is to check the function of gutters, downspouts and general drainage around the house. Making sure that water can move away from the foundation is a reliable way to limit soil movement in the area immediately surrounding the building.
Improving exterior drainage can help prevent future damage from expansive soil, but it can’t correct damage that has already occurred. When a foundation wall has been pushed inward because of pressure from expansive soil, the repair strategy may involve installing wall anchors in the damaged wall to stabilize it and actually pull the wall back toward its original plumb position. Different types of wall anchors are available but they all work in the same way. A strong steel rod extends from the exterior anchor point through the foundation wall and through a large steel plate that distributes clamping pressure as a nut is gradually tightened on the rod’s threaded end.
Another way to stabilize and correct bowing or tilting foundation walls is to install steel I-beams against the wall from inside the basement. The patented PowerBrace™ I-beam system available from Foundation Supportworks® contractors has an excellent track record with repairs of this type.
Ayers' Basement Systems provides expert foundation repair in Lansing and other surrounding areas. Visit them online for a free foundation repair estimate in Michigan!
