Foundation Heaving Repair Experts Serving Greater Toronto

diagram of foundation slab that is experiencing upheaval

Foundation upheaval can lift an entire structure, but more often it forces parts of a foundation or slab upwards, creating cracks and uneven floors.

If you have seen cracking floors or walls, sticking doors and windows, and uneven surfaces in your home, you could have a foundation heave problem. Foundation heave occurs when a foundation or concrete slab is forced upward by the expansion of soils underneath.

This process creates a number of issues in a home, and it can lead to very severe damage. The foundation experts at Clarke Basement Systems can repair your foundation repair problems and ensure that your home is structurally sound.

Telltale Signs of Foundation Heave:

  • Cracking On Inside Walls (Common)
  • Cracking On Outside Walls (Rare)
  • Cracks On The Concrete Floor Slab
  • Displaced or Tilting Slab Sections

If you've seen any of these problems in your home, call us today to learn more about how we can fix your heaving foundation in Markham, Vaughan, Mississauga and nearby areas in Ontario.

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 is most commonly caused by these four forces:

samples of wet and dry clay

Expansive Soils

A house built on soils with high clay content will be susceptible to heaving forces because clay-rich soil expands significantly when it gets wet.

The excavation for a foundation often gives the soil around and under a house a chance to dry out and shrink, as shown in the photo at right. After the house is built, clay-rich soil that gets soaked during wet spells can cause heaving problems while also damaging foundation walls.


Frost on a grassy hill with a frost-covered tree.

Frost Heave

Water increases about 9% in volume when it freezes, wet soil can expand by at least that amount upon freezing. When this happens, the resulting pressure on a slab or foundation can cause it to shift and crack.

The colder the temperature, the deeper the soil will freeze. In frigid temperatures, foundations that were not built below the "frost" or freezing line.

Frost forces can lift a foundation upwards dramatically, sometimes by several inches or more, leading to serious frost heaving damage. to a foundation.


Diagram of a broken pipe underneath a foundation slab.

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 HVAC systems.

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.


Heavy rains in a downpour in Aurora.

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, buckling walls.

What NOT To Do:

cracks in a slab floor consistent with slab heave in Clarington.

Cracks on floor slabs that are caused by foundation heave are unique in appearance.

You will see multiple cracks that come together to a point or form an enclosed loop where the heave is greatest.

Before conducting any foundation repairs, it's important to identify the problem as heaving. Some contractors who have not been fully educated on the signs of heave can easily misread the cracks in your home and suggest the wrong solution.

The problem? While heave is the opposite of foundation settlement, the symptoms are often similar. To an untrained eye, it may appear that the exterior walls are going down -- when the reality is that the basement slab is being pushed up near the center of the house.

To apply the right solution to a foundation problem, make sure you're getting the right diagnosis.

The right way to fix heaving slabs

Since unwanted water accumulating in the soil and the associated pressure is typically the cause of slab and foundation heave, Clarke Basement Systems' 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 the following repairs:

  • 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, the experts at Clarke Basement Systems are here to evaluate your foundation heaving problems and suggest the best solutions for your home.

We are your local foundation heave repair experts!

At Clarke Basement Systems, we have all the best tools and training available to fix foundations and slabs that are experiencing problems with upheaval. If you're having any problems in your home, call us today to set an appointment with one of our foundation specialists and get a free quote! We proudly serve in Mississauga, Markham, Vaughan, Oshawa, Vaughan, Brampton, Barrie, Peterborough, Newmarket, Richmond Hill and throughout the surrounding areas.

Looking for a price? Get a no cost, no obligation free estimate.

our service area

We serve the following areas

Our Locations:

Clarke Basement Systems
12045 McCowan Rd
Stouffville, ON L4A 4C3
1-416-800-3177


Clarke Basement Systems
7250 Keele St Store #209
Vaughan, ON L4k 1Z8
1-416-800-1687