Fine grained soils (clays) are often sensitive to changes in soil moisture content; when dried they shrink and when wetted they swell. When paired near large trees, the resulting ground movements can wreak havoc with a building’s interior walls and foundation.

The Allen Park Housing Commission provides housing assistance to low income senior citizens through the rental and management of low rent public housing. These rentals are located at The Leo Paluch Senior Apartments in Allen Park, Michigan. The apartments are housed in a three-story, slab-on-grade 30,000-sf building constructed in the 1960s. SME was retained when four of the apartments experienced up to 1-inch wide cracking in the exterior brick and interior drywall, as well as slab settlement along the perimeter of the building. We performed hand auger borings inside the apartment buildings and a soil boring at the exterior of the building to explore the soil and groundwater conditions. 

SME found the soils were mostly highly plastic with a propensity for large volume changes from changes in the moisture content of the soil — when dry, there was great shrinkage and when wet, there was great swelling. This resulting ground movement introduced problems with the building’s foundation. 

Large trees can also create issues. By removing water through their root systems, the trees cause a local drying out of the soil resulting in non-uniform settlement that can cause cracking in buildings. This is what occurred here. The project site had two large oak trees near the affected four units. The trees reduced the moisture in the subsurface clays, and to make matter worse, this area experienced minimal rainfall during the summer. The soils shrunk, causing settlement and cracking of the building.  

The Allen Park Housing Commission followed our recommendations and cut down the trees near the units. SME then installed crack monitors and performed an elevation survey of the foundations near the distressed portion of the building. After the trees were removed we observed that the cracks in the exterior brick closed up some, and the foundation rebounded.