Why do foundations settle or sink?
Why are there cracks in my foundation?
When the soil beneath your home is no longer stable enough to support the structure, it compacts and shifts, causing your house to settle or sink. You notice this through cracks in walls, uneven floors, or sticking doors and windows, among other symptoms.
Unstable soils can be caused by:
- Hydrostatic pressure
- Soil washout
- Soil shrinkage / soil expansion
- Poorly compacted fill soil
- Poor drainage / poor water management
- Tree roots
Hydrostatic Pressure
Hydrostatic pressure occurs when the water in the soil outside of your home’s foundation, such as the basement, exerts pressure against the block foundation walls.
At 60lbs. per cubic foot, water in the soil can exert thousands of pounds of pressure against your basement walls. This pressure ultimately causes bowing, cracking, and water leaks.
Soil Washout
Soil washout refers to the rapid erosion of soil caused by water, typically heavy rain or flooding. This creates voids in the soil that cannot support the weight of the structure above it.
The building compacts the soil beneath it into the void that’s been created and settles along with it. As the structure shifts, floors become uneven, windows and doors stick, and cracks in walls appear.
Soil Shrinkage / Soil Expansion
Soil shrinkage is a result of soil being too dry, usually during a drought or heat wave. Soil expansion occurs when soils swell with water.
Different types of soils, such as clay, sand, and loam, have different shrink/swell potential in relation to their change in moisture content. For example, clay soil tends to hold more water and shrink more than sandy soil.
Poorly Compacted Fill Soils
When homes are built, soil is moved to level lots. When these “fill soils” are used to fill in the valleys and create a flat area to build are more in, they are not always compacted evenly.
Poor Drainage & Water Management
Water sitting against the home’s foundation contributes to the saturation of the soil. Water also follows the path of least resistance, so it will push its way into basements and crawl spaces, causing mold, mildew, and wood rot.
Overflowing or absent gutters, improper downspouts, and extensions all allow water to pool against your home, causing more damage to your foundation.
Tree Roots
As trees grow, their roots pull more moisture out of the soil, changing the soil conditions around the home. This can contribute to the expansion and shrinkage of soil.
In some cases, roots may become invasive and exert pressure on your foundation walls, causing damage to underground plumbing or sewage line,s which could result in more soil saturation and pressure against your foundation.
What to look for:
- Stair step cracks in bricks or cinderblocks
- Cracks around windows and doors
- Vertical wall cracks
- Chimney separation
- Bowing walls
- Sticking windows and doors
- Uneven floors
If you notice any of these symptoms, it’s always a good idea to have a foundation professional evaluate your home to determine if you have foundation settlement issues.
The Drying Company is ready to help you repair your home’s foundation and give you peace of mind. Call for a free foundation inspection at 1-757-566-8622.
