One of the most common questions being asked of us is, “why is my foundation having a problem?” The answer is that while there can be many reasons for a foundation problem, the most common is that the sub-grade beneath the slab has developed an uneven moisture content. That is to say that some of the soils under the slab have more moisture and some have less. When this happens in soils with expansive characteristics, it can result in dramatic soil change. The wetter soils swell, while the drier soils contract. Depending on the type of soil, these movements can be substantial, sometimes up to several inches or more.
In an ideal scenario, ALL soils beneath a slab would keep the same moisture content, expanding and contracting uniformly as the weather/rainfall dictated. This results in the slab rising and falling very slowly, as well. And, since this movement is slow and uniform, across the entire slab, no damage occurs. But, this is rarely the case. More commonly, the following scenario occurs. The soils under the center of the slab tend to maintain a more constant moisture content and therefore, are more stable. However, the soils near the slab perimeter often undergo dramatic moisture change. During dry weather, these soils dry out due to factors like trees, plants and evaporation. As expansive soil dries, it contracts. A term to describe this scenario is “differential movement.” So in different areas, the soils (and slab) are moving differently. This is often noticed as distress (cracks) in masonry, sheetrock, and misaligned doors or separations in trim.
This movement can easily be identified by conducting an interior elevation survey of the slab. Power Lift uses a computerized level to perform these surveys. The equipment is very accurate and the survey can be performed quickly. Affected areas of the slab can be treated effectively with our driven steel piles and often can be lifted to align with the interior.
Our estimator’s are experienced at analyzing these problems and at designing effective solutions. And, our estimates are free to homeowners. Let us put our experience to work for you!