What are pitfalls to avoid when maintaining a foundation on expansive soil?
• Never allow the soil around and below the house to become dry during extended dry periods. Highly expansive clay soil will shrink in volume and allow the foundation to settle downward. The foundation will experience “differential settlement” which is detrimental to the building structure if the soil at the perimeter foundation dries before the soil under the floors. The soil usually dries slowly under the floors because its moisture is trapped by the floor of the building. • Never apply water directly into the gap that opens between the concrete slab and the soil during extended dry periods. Water flowing under the concrete grade beams that make up the support the building will dissolve the clay in the soil below the beams and carry it away into the cracks that form in the yard as the soil dries. Soil carried away in this manner is lost and so is the height that it contributed to the elevation of the foundation. • Never allow the surface of the soil immediately adjacent to a concrete
