Void forms are used in the construction of cast-in-place concrete foundations where expansive soils are present. Void forms provide temporary support for cast-in-place floors, beams and walls until the concrete can support itself on the drilled piles or caissons. Over time, the corrugated paper that is used in the construction of the void form will absorb moisture from the surrounding enviroment. This moisture causes the void form to lose its structural integrity, thus allowing the soil to expand without causing damage to the foundation.

Where expansive soils are present, cast-in-place foundations on void forms are a must. The initial cost of a foundation on void is minor compared to the cost of repair and business downtime associated with repair.