San Tan Valley Foundation Repair

Friday, February 5th, 2021 by Jessica LaFlesch

Challenge

The owners of this 2004 ranch family home reached out to us after noticing a few symptoms of a foundation problem. This included interior wall cracks, exterior cracks in the stucco as well as unlevel floors.

After examining the home and performing the manometer survey, Arizona Foundation Solutions believes the home could be experiencing minor foundation settlement at the northeast portion of the home as shown by the lower readings on the topographical map. The drop off in floor elevations on the topographical map is consistent with a foundation settlement pattern. Settlement can be caused by one or any combination of many factors including sub-grade saturation of moisture due to poor drainage, years of storm runoff, plumbing leaks, improper compaction, the lack of a proper foundation system, and/or (in most cases) natural earth movement.

A minor foundation heave pattern is observed in the northwestern portion of the home as indicated by the higher elevation readings on the 3D topographical map. This phenomenon usually occurs in areas where structures are built on expansive clays. Moisture from one or any combination of the following: storm runoff, poor drainage around the foundation, plumbing leaks and/or underground moisture sources will allow the moisture/vapor to accumulate underneath the foundation. The moisture then interacts with the clayey soils, causing them to swell. The clay soils take the path of least resistance and expand upwards and lift the foundation.

Solution

Arizona Foundation Solutions believes that the proper way to permanently stop the perimeter foundation settlement is to underpin the areas that are experiencing movement. Underpinning is the process of installing deep foundation elements called piles. Piles are engineered foundation supports that are driven down past the unstable soils and are then locked up into load bearing strata, which can support the loads that are transferred to them. Once the piles have been installed, they can be used to lift the perimeter foundation up to its Highest Practical Maximum. The piles should be spaced approximately six to eight feet on center and should start and stop near the hinge points of movement (exact spacing to be determined after load bearing calculations). In this case, the piles would be located at the northeast portion of the home. The slab can then be treated by injecting a lightweight expansive polyurethane to fill existing voids and lift the floor slab. This is done by drilling small 5/8” holes in the slab after which polyurethane grout is injected directly under the slab to raise it up to its Highest Practical Maximum. Using the expansive materials will help prevent additional foundation slab settlement by compacting the upper layer of soil as it expands.

Arizona Foundation Solutions believes that the proper way to deal with foundation heave is by lowering and managing the moisture content of expansive clays that cause heaving. It is our recommendation to manage the moisture underneath the foundation through active soil depressurization. This process will remove existing moisture from the soil as well as new moisture from the expansive clays and will help bring the moisture content down to an optimal level using both convection and evaporation. This will mitigate future heaving of the clay soil and possibly allow existing heaving to subside. This process can take six months to several years to reach equilibrium.

The Moisture Level® Smart Foundation System is designed to control the moisture of expansive clays that cause heaving under the home. If optimal results are not achieved with the Moisture Level® Smart Foundation System, including additional measures described below, more aggressive measures may be required. The manometer and foundation survey will act as a baseline to measure performance over time.