Foundation Repair

While sandy soils remain stable as water passes through them, soils rich in clay undergo significant changes based on their moisture content.

When clay type soils dry out, they shrink significantly — so much that the ground can become covered with cracks. But after a heavy rain, the cracks are gone and the soil is fully saturated with water.

Because clay soil absorbs so much water, it expands during wet weather.

Expansive clay soils can put enormous pressure on your basement or foundation walls. When the pressure becomes more than the wall can handle, the wall will begin to push inwards.

Hydrostatic pressure is the pressure exerted by a fluid due to the force of gravity.

To understand how hydrostatic pressure can damage foundation walls, imagine how much heavier soil becomes when it’s soaked with water. When the weight of water is added to the weight of the soil, you’ve got much greater pressure pushing against a foundation wall.

Hydrostatic pressure effectively amplifies soil pressure against a foundation wall. When the pressure exceeds the foundation wall’s ability to withstand it, the wall will begin to bow, buckle, tilt inward at the top, or move inwards at the bottom.

In areas with cold winter climates, frost heaving can sometimes put enough pressure on foundation walls to make them fail.

When water turns to ice, its volume increases by about 9%. If wet soil experiences a deep freeze, the wedging or heaving force that results can be extremely powerful.

Frost heaving can put literally thousands of pounds of force against your foundation walls, causing cracks, bowing, and heaving.

Foundation soils experience most of their drying and shrinking from two common causes:

Drought: Prolonged dry periods cause the soil to dry out. As we know, when the clay dries out, it shrinks. Soil shrinkage beneath a foundation has the same effect as soil settling: It usually causes a section of the foundation to crack and settle into the void or hollow area where settlement has occurred.

Maturing Trees: The root system of a tree can be up to twice the size of the tree’s canopy. If a tree’s branches extend over your home, there’s a good chance that they extend under your house as well, drawing moisture up from the soil and causing it to shrink.

The soils around your foundation experience wetting and softening primarily for these three reasons:

Heavy Rain & Flood Conditions: As clay soil gets wet, it holds on to water and becomes very soft. This soft soil can be weak, causing the home to shift (or “sink”) down into it.

Poor Drainage: If water is allowed to stand or “pond” next to your home, the soil will absorb the water. As it does, the soil can weaken and soften once again.

Plumbing Leaks & Broken Water Lines: When a home’s plumbing begins to leak under a slab foundation, the soils underneath can begin to become saturated, weakening their supporting capacity.

In order to level a site where a foundation will be built, builders sometimes bring in loose soil from another location to fill depressed or hollow areas.

This newly moved “fill” soil is much looser and lighter than the dense, hard-packed virgin soils at the site that haven’t been disturbed.

The fill soil brought in by the builder has to be compacted thoroughly before a foundation is built on top of it. If the soil is not compacted well, it may begin to compress underneath the weight of your new home, creating settlement problems that can damage your foundation.