Underpinning a house means transferring the structure’s load to soil that can support it. The piers used in underpinning go deep down past unstable ground to firm substrata. Transferring the building’s load to strong soil not only stops settlement and adds additional support to the foundation. Underpinning a house can also preserve the value of the structure.

REASONS TO CONSIDER UNDERPINNING YOUR HOME

Underpinning a house is necessary when the home’s foundation is no longer able to support it. This usually isn’t a problem with the foundation itself but the ground underneath. Less than ideal conditions under a foundation include:

• Expansive soil – This is soil that contains a significant amount of clay, which swells when wet and shrinks when it dries out. This swelling-shrinking cycle – which usually happens on a seasonal basis – creates movement, putting stress on the foundation, eventually causing pockets to form under the foundation.
• Soil insufficiently compacted before construction – Soil removed from a construction site and then used as backfill material needs to be well compacted. Failure to do so may result in the structure settling into the soil unevenly, eventually leading to structural damage.
• Soil erosion – Caused due to poor drainage around the home.
• Soil creep – Soil moving away from the foundation and causing lateral movement in homes built on hillsides.

Other problems that might make underpinning a house necessary include:

• Poor construction – The contractor built the house without taking into consideration the underlying soil type.
• Renovations – Adding a story to a house will add significant weight to the foundation, placing unaccounted for stress on the original substructure.