Foundation heave is the upward movement of the expansive soil layer after it is saturated with water. Controlling the signs and symptoms of foundation heave at an early stage is important to prevent further enlargement of heave pressure and avoid serious damage to the foundation and superstructure.
Common signs of foundation heave are cracked and bowed slabs, cracks in drywall, brickwork, doorframes, lifted sidewalks, tilted slab sections, etc. These signs are considerably concerning and create an unpleasant appearance. Additionally, they may interfere with the functionality of the building and disrupt the quality of life.
What are the Signs of Foundation Heave?
Some of the signs observed before a foundation heave are:
- Cracks looking like spider webs or chicken feet with at least two intersecting cracks. Cracks intersect and create a triangle shape at a location where heave is the greatest.
- Concrete damage due to foundation heave during or immediately after construction, which accelerates few years after completion.
- Trees around the structure fall or die a year or two after the first distress is noticed.
- Flatwork like driveway, patios, and garage slabs adjacent to the foundation translates upward and away relative to the foundation.
- Water Leakage is observed from under slab plumbing, pools or ponds nearby the building.
- Increase in the moisture content of the upper soil layer underneath the foundation. The soil plasticity index is greater than 25.
- The soil beneath the perimeter beam is easy to probe.
- In-ground pool near the structure is out of level.
- Drainage of the site on which the structure has been constructed is sloping toward the foundation.
- Excavation around the foundation reveals wet, muddy soil in the upper few meters below the perimeter grade beam.
- The gaps between grade beams, piers, or foundation repair shims are loose.
- There is no space between the perimeter grade beam and the adjacent soil at grade.
- Large amount of damage to the foundation and superstructure for a relatively small amount of level distortion in the foundation.
- Damage in the ground-level flooring materials.
- Slabs are bowed between grade beams, and the grade beams are connected to piers constructed well below the active zone.
- Development of cracks in drywalls, brickworks often in a zigzag form, at the top of the doorframes, and top and bottom of window frames. These cracks will grow thicker and longer over time.
- Frames of windows and doors become out of square due to constant upward pressure on the foundation, which is transferred to a framework, making doors and windows sticky.
- Lifted patios, garden sheds, and sidewalks.
- Tilted slab sections.
1. Cracks in slabs
2. Sticky doors and windows
3. Bowing of slab
4. Lifted sidewalks and other flat work
5. Cracks on the interior face of walls
Cracks on the exterior face of walls due to foundation heave are uncommon.
Cracks in drywall and brickwork, often in a zigzag form, at the top of the doorframe, and top and bottom of window frames. These cracks will grow thicker and longer over time.
The increase in moisture of a soil layer below the foundation in recent years is a common sign of foundation heave.
Yes, it is possible, and some occupants may not notice it immediately. However, the signs of foundation heave can disrupt the quality of life and even interfere with the functionality of the building.