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How does Poor Drainage Cause Foundation Settlement?

Poor drainage is a leading contributor to foundation settlement because it disrupts the stability of the soil supporting a structure. When water is not properly routed away from a home, it saturates the ground, leading to two primary destructive processes:

  1. Soil Erosion and Voids:

Saturated, waterlogged soil can erode over time. When water pools near the foundation due to improper grading, clogged gutters, or short downspouts, it can wash away fine soil particles from under the footings. This creates hidden voids, leaving the foundation without adequate support and causing it to settle unevenly.

  1. Soil Volume Changes:

In regions with expansive clay soils, such as Colorado, poor drainage is particularly damaging. These clays swell dramatically when saturated and shrink as they dry. This cyclical movement creates a back-and-forth stress that weakens the foundation’s integrity. Additionally, loose fill soil that was not properly compacted during construction will compress further when it becomes saturated, accelerating the settlement process.

Warning signs of drainage-related settlement include:

  • Standing water near the foundation after storms.
  • Uneven or sloping floors.
  • Damp crawlspaces or efflorescence (white powdery residue) on basement walls.
  • Sticking doors and windows.
  • Cracks in interior or exterior walls.

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