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How Different Soil Types Impact Your Foundation

How Different Soil Types Impact Your Foundation

 

Sandy soil (left) and sandy loam soils (middle) expand and contract very little with moisture changes. They can be very reliable when supporting a foundation.

Clay soils (right) expand and shrink in volume dramatically with moisture changes and can cause significant foundation damage.

Sandy Soils & Your Foundation

Water passes through sandy soils rather than being absorbed. This fact makes sandy soils very stable. Instead of expanding as they absorb moisture and contracting as they dry out, sandy soils maintain a fairly consistent volume and density.

Because of their stability and good load-bearing qualities, sandy soils are less likely to shift and settle, so they rarely cause foundation problems. Unfortunately, sandy soils are less commonly found than other more problematic soil types.

How Clay Soils Affect Your Foundation

Soils rich in clay and silt have the greatest potential to damage a foundation. Clay absorbs water easily, expanding in volume as it becomes more saturated. So-called “expansive clays” can cause foundations to crack, heave and shift.

When clay soils dry out, they shrink and crack, leaving gaps around a house where water from the next storm can penetrate easily and deeply to repeat the expansion cycle. Clay-rich soils usually cause more foundation damage by expanding than by contracting.

Sandy Loam Soils

Loamy soils are usually a very stable soil that shows little change with the increase or decrease of moisture temperature.

The primary concern with foundations built on loamy soils is erosion. When soils underneath your foundation erode, they may begin to be inappropriate strata for sustaining the weight of a foundation and home structure.

Call MBRGFR Today for a Free No Hassle Evaluation 817-469-1090






Drainage and Foundation Repair

5 Tips for Foundation Drainage 

Keeping water drained away from home foundations is important for two main reasons. First, if there is living space on the other side, the owner will want it to stay dry. Good drainage is the first step toward accomplishing that, then waterproofing. Second, soils supporting a foundation need to stay at a consistent moisture level to prevent settlement, heave, or differential movement.

Here are a few things to keep in mind

  • Moisture: There are two zones of subsurface moisture: the aeration zone (where both water and air exist) and the saturation zone. Generally, the saturation zone is everything below the water table, which is the level at which water rises to in a well. The saturation zone is seldom an issue in residential construction—soil moisture is the concern.
  • Loss of soil moisture: Soil moisture beneath a foundation is lost in a triangular configuration, so the deepest dry area is just outside the edge of the foundation and the ground beneath the middle of the slab remains saturated. Differential drying or differential amounts of moisture in the soil can create problems, especially in expansive soils.
  • Surface drainage: Controlling surface water is critical to controlling soil moisture beneath the foundation. The ground surface should slope away from the house at between ½ and 1 inch per foot for at least 6 feet—10 feet is better. Be careful of poorly compacted backfill, though, because that will soon mean that the surface will slope back toward the house.
  • Gutters: Downspouts should discharge on sloping surfaces at least 6-10 feet from the foundation. Where that isn’t possible, downspouts should discharge into drained catch basins.
  • Finally, remember that it is much easier to do foundation drainage right in the first place than to repair it later.

Think you may have a Drainage or Foundation Problem?, Call us 817-469-1090 For Your Free Evaluation