Excessive moisture build up in expansive clay soils can cause the ground to swell and this may cause a lifting of the interior floor slab or the foundation in general.
As expansive clay soils are dried out, this loss of moisture can cause the ground to shrink and a settling of the interior floor slab or the foundation can occur.
Extra work above and beyond the original contract repairs may be necessary because of unforeseen or unpreventable conditions that exist around the foundation. Because foundation repairs are below ground and not visible, the cause of problems is not always evident and the fix may not be easily diagnosed.
1. Expanding Foundation Soil – Dry expansive clay soils present during the construction of a foundation will begin to expand as moisture is absorbed by the soil. This expansion will create a lifting movement in the foundation and can last anywhere from 5 to 10 years after construction. If there is a foundation problem within the first 5 years after construction, it is highly recommended that a soils test be performed.
2. Shrinking Foundation Soil – Wet expansive clay soils present during the construction of a foundation will begin to shrink as moisture is naturally drained and pulled away from the soil. This shrinking soil will create unsupported areas and a settling of the foundation. This foundation settle can occur over many years.
3. Seasonal Moisture Variations – Changing moisture content in expansive clay soils can have an impact on a foundation. When seasonal water levels fluctuate the expanding and shrinking soil can cause movement in a part of or across the entire foundation. The changing underground water levels can be caused by poorly graded slopes, areas of trapped water, sub-surface springs, and changing water tables.
4. Vegetation – If located adjacent to foundations, root systems from trees and large shrubs may accelerate moisture removal from the soil causing the ground to shrink, creating non-supported areas and the foundation or interior floor slab may settle as a result.
5. Leaking Pipes – If there are leaks in pipes near a foundation, the added moisture in expansive clay soils will create a swelling and expansion of the ground potentially causing a heaving of the foundation. After a fix has been made to correct leaks in plumbing, the expansive clay soils will begin to dry and contract creating voids in which the foundation can settle into. These changes and settling of the foundation can take place over an undetermined time-frame from just weeks to over many years.
6. Incorrect Fill Soil Compaction – A number of problems can occur if proper procedures are not followed in the compaction of the fill material used to level the foundation site. Testing and supervision should be performed by a geotechnical engineer to determine the proper layering of the fill. If the material is compacted too much it may expand back over time creating a rebound heave. If the material is not compacted enough it may settle and allow the foundation and the slab to lose support and drop.
7. Silty or Sandy Soils – Silt and sand in the layers on top of expansive clay may create a path for moisture to quickly infiltrate the ground near the foundation. Depending on the season, this rapidly changing moisture content may cause the soil to move and create a lifting or shift of the foundation.
Causes of Foundation Failure
- Plumbing leaks
- Poor soil conditions
- Hydrostatic ground pressure and water pressure
- Improper back fill
- Plugged drain tile
- Sump pump set incorrectly
- Different soils
- Low ground
- Drain tile not connected to bleeders
- Concrete slanted to house
- No gutters or no downspouts with extensions
Signs of Foundation Failure
- Doors & Windows open/shut hard
- Plaster is cracking on walls
- Frames around doors and windows separate
- House making noises
- Cracking mortar on brick outside
- Siding buckling
- Sloping floors
- Plumbing lines bent
- Step cracks on blocked walls
- Cracks in poured walls
- Wall ties leak
- Water seeping between the floor and the wall
- Water from cracks in the floor
- Mold/mildew on walls