What Foundation Repair Requires: Piers or Shims?
Foundation repair can involve either piers or shims, but the choice depends on the cause and severity of the settlement. Piers are used for deeper, more severe subsidence where the foundation has moved significantly or is unstable. Shims are a lighter, faster solution for minor, localized settlement that can be corrected by adding material beneath the foundation to level it.
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When Piers Are Needed
Piers are driven deep into the ground or installed in drilled holes to reach stable soil or bedrock. They provide a vertical support system that lifts the foundation back to its original level. Piers are preferred when:
- The settlement is large or uneven across the structure.
- The soil is soft, loose, or has a high water table that cannot support a shimming approach.
- The foundation is at risk of cracking or further movement without substantial support.
Installation involves drilling a hole, inserting a steel or concrete pier, and pouring concrete to lock it in place. The process can be completed in a few days, but it requires significant excavation and may affect surrounding landscaping.
When Shims Are Appropriate
Shims are small wedges of wood, plastic, or metal that are inserted between the foundation and the ground to fill gaps and level the structure. They are suitable for:
- Minor, localized settlement that does not compromise structural integrity.
- Situations where the soil is relatively stable and does not require deep support.
- Homeowners seeking a quick, less invasive fix.
Shimming involves removing soil, placing wedges, and sometimes adding a concrete or stone layer to hold the shim in place. It is generally less expensive and faster than piers but does not address underlying soil instability.
Comparing the Two Methods
| Attribute | Piers | Shims |
|---|---|---|
| Depth of support | Deep (up to 30 ft) | Shallow (top few inches) |
| Cost | Higher | Lower |
| Installation time | Days to weeks | Hours to days |
| Long‑term stability | High | Moderate, depends on soil |
Making the Decision
A qualified foundation specialist will assess soil conditions, settlement extent, and structural damage. If the foundation has sunk more than an inch, or if cracks are present, piers are usually the safer choice. For light, uneven settling where the floor feels slightly uneven, shims can provide an adequate fix. Consulting a licensed engineer or foundation contractor ensures the selected method will protect the home's value and safety for years to come.