Foundation Restored for Home Built in 1800s

Challenge

Gordon and his wife live in a one-story home built in the 1800's, with limestone walls and a basement. Gordon noticed a growing gap at the top of an exterior wall on his house. He had been filling it in with foam, but it kept opening up. It was visible where the wall had shifted in and left a gap between the sill plate and the top of the wall. Gordon and his wife often traveled for long periods, and they were concerned they might come back to a garden in the basement or that the house would fall down if they didn't do something about this problem soon. Gordon contacted Thrasher when he noticed the void at the top of the exterior wall was getting bigger, and they were worried they wouldn't have a home to come home to. They chose Thrasher because of our expertise, professionalism and warranties. 

Our foundation specialist found one basement wall of the house was very unstable during our inspection of the home. The homeowner had removed some of the paneling from the wall and had to stop when he discovered the paneling seemed to be the only thing holding the loose limestone foundation back. The customer was aware of how urgently the wall needed to be repaired and how its condition had become a severe wall problem.

The Problem

As forces of nature, such as moisture and frost, interacted with the soil around Gordon's home, the soil expanded. That expansion resulted in constant inward force on his foundation wall until it could no longer support the pressure, causing cracking, bowing, and tipping. Unfortunately for Gordon, the integrity of using stacked limestone and mortar could not withstand these pressures. 

The Root Causes

Water is the root of most soil expansion. Wet foundation soils have several possible ill effects. Adding water to soils causes them to expand, add weight to the ground, and put enormous pressure on your foundation walls.

Wet soils can lead to foundation damage in three ways:

Cause #1: Expansive, Wet Clay Soil

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. Sometimes, this shrinkage causes the ground to 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 inward.

Cause #2: Hydrostatic Pressure

Hydrostatic pressure is the pressure exerted by a fluid due to the force of gravity. Imagine how much heavier soil becomes when it's soaked with water. When the weight of water is added to the soil's weight, you've got much greater pressure pushing against a foundation wall.

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

Cause #3: Frost Heaving

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 thousands of pounds of force against your foundation walls, causing cracks, bowing, and heaving.