How Heaving Foundations and Slabs Lead to Damage of Your Home

Have you noticed cracks in the walls of your home, cracking concrete floors, or displaced or tilting slab sections? If so, your foundation or slab floor is moving upwards, leading to cracks in the walls and floors of your home.

What Causes Foundation Upheaval?

Heave is the upward movement of a foundation or slab caused by underlying soils that expand or swell. This occurs due to an increase in moisture or by freezing forces. Heave is more common with slabs than foundations because slabs have less weight to resist heaving forces. Unless there is a long period of drought, heave most commonly occurs within the first few years of the building's construction.

Slab and foundation heave are most commonly caused by these four forces:

• Expansive soils: Soils with a high clay content expand significantly when they get wet. The excavation for a foundation often gives the soil around and under a house a chance to dry out and shrink. After the house is built, clay-rich soil that gets soaked during wet spells can cause heaving problems while also damaging foundation walls.
• Frost heave: Water increases in volume by nearly 10% when it freezes, and wet soil can expand even more when frozen. When wet soil freezes the resulting pressure can cause the slab or foundation wall to shift and crack. The colder the temperature, the deeper the soil will freeze. Frost forces can lift a foundation dramatically - sometimes by several inches - leading to serious heave damage.
• Plumbing leaks: Leaks or breaks in plumbing lines that run underneath a concrete slab or through a foundation wall can deposit moisture underneath the foundation and slab. This moisture can be from supply lines, waste lines, or even your home's HVAC system. Over time, this moisture can cause the soils underneath the foundation to expand, which will then cause them to push up on the structure above.
• Prolonged or heavy precipitation: Too much precipitation combined with too little drainage away from the house will lead to increased moisture underneath your foundation. Moisture that comes into contact with expansive soil can result in heaving of your foundation and slabs. Precipitation can also cause expansion in the soils on the sides of your foundation, leading to bowing, bucking walls.

How We Solve Foundation Heave

Be sure it's foundation heave. Foundation heave and foundation settlement have similar symptoms, and to the untrained eye it may appear that foundation walls are going down when in fact the floor is coming up. However, the solutions to these two problems are very different, making it essential to get a correct diagnosis.

Since unwanted water accumulating in the soil under your home - and the pressure it brings -- is typically the cause of slab and foundation heave, our first priority will be to eliminate water sources wherever possible. We will check for underground water line leaks, clogged drains, broken sprinkler lines, as well as faulty gutter and leader systems.

Once we have fixed water problems, we can begin making repairs like:

• Concrete grinding for minor heaves, especially in outdoor slabs
• Soil stabilization by polymer injection to resist water infiltration
• Mechanical foundation repair, including the use of helical piers that can both support your foundation and to keep it from heaving in the future

Other causes for heaving include tree roots and pressure from adjacent buildings. Regardless of the cause, an authorized foundation contractor is the best person to evaluate foundation heaving problems and suggest suitable solutions for your home.

Contact the Foundation Heave Repair Experts

At Thrasher, we have the tools and training available to fix foundations and slabs that are experiencing problems with upheaval. We offer foundation and slab heave repair inspections to all within our Nebraska, Iowa, and Missouri service area.