Foundation Repair Case Studies: Foundation Restored for Home Built in 1800s

Monday, October 1st, 2018

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.

 

Solution

We used two different available products, wall anchors and shotcrete wall restoration products, for this foundation repair project. 

The GeoLock Wall Anchor System permanently stabilizes the foundation wall and, in many cases, can straighten the wall back toward its original position. Heavy-duty earth anchors are embedded in stable soil away from the foundation wall and connected to steel wall plates with long, galvanized rods. Once tightened, the anchors will hold the wall securely in its current position without any further adjustment. When not utilized in conjunction with the ShotLock Restoration System, the system's unique benefit includes the ability to tighten the anchors during dry seasons, meaning walls can be improved and even wholly straightened over time. 

Our shotcrete solution, known as the Shotlock Restoration System, permanently stabilizes foundation walls that have deteriorated excessively. Even in cases where foundation walls have extreme damage, or when the walls are constructed with inadequate building materials such as stone, rubble, brick or clay tile, the ShotLock Restoration System offers a long-lasting solution. 

ShotLock utilizes a fiber-reinforced concrete material conveyed through a hose and pneumatically projected onto a wall surface. Due to the high force used to adhere to the wall, the material undergoes a significant compaction process during installation that produces more than two times the strength of regular concrete, making it the ideal solution for deteriorating basement walls. When ShotLock is installed in conjunction with vertical reinforcements, such as GeoLock Wall Anchors or PowerBraces, foundation walls will be stable, solid, and completely restored. 

In this instance, the GeoLock Wall Anchor System, in conjunction with the ShotLock Restoration System, was utilized for Gordan's home. 

The Process

First, the Thrasher crew cut holes in the paneling and installed wall anchors. They estimated the wall had shifted and come in about 8-10 inches. They could pull the limestone basement wall back 5-6 inches and secure it with the anchors. The wall was then prepped for the ShotLock Shotcrete Wall Restoration System, with rebar, metal caging and angle iron frame. The next day, ShotLock product was applied, leaving Gordon with a worry-free, stable and safe new wall that will stand the test of time. We protected his home from the potential for further damage, which would have cost more and taken much longer to repair – not to mention the danger of living in a house with a wall that could cave in at any moment. Additionally, because of the age of the home and Gordon's plans to someday turn his basement into a man cave, he opted for a SaniDry basement air system to help keep the building materials dry and make the basement space healthy and comfortable.

The SaniDry basement air system utilizes a SaniDry Sedona to eliminate dampness, musty by drying and filtering the air! Mold and mildew are musty smelling fungi that thrive in moist conditions. Dust mite fecal matter is the #1 indoor allergen. The SaniDry Sedona keeps a space below 55% Relative Humidity – mold won't stand a chance, and dust mites will die off! 

These solutions worked for Gordon, and he was able to save his home and gain his man cave in his forever home. 

If you need help with any of these problems, like Gordan had, please contact us and have a free estimate performed to provide a permanent solution to your worries.