Footing Soil Stabilization Saves Historic Mansion in Iowa

The Challenge

Soils beneath the Henn Mansion foundation became weak and the building began to settle.

The elegant Henn Mansion, located in Fairfield, IA, was originally built to be the home for the President of Parson’s College in 1857. In 1983, the mansion was added to the US National Historic Register, and today the building serves as the Human Resources office for Maharishi University. Over the years, soils beneath the building’s foundation became weak and the building began to settle with serious cracks developing at the southeast corner.

Back in 1857, the footing of Henn Mansion was designed as a “continuous” footing. That means the limestone rock used as the footing is in continuous contact with the soils below. The settlement of the building’s foundation was caused by the loss of support within the soils under the continuous footing. Since the building’s footing was constructed of limestone rock, it couldn’t be repaired with traditional pier methods since there is no place to attach the anchor brackets. Another consideration involved the fact that the building is in active use as a university administrative office, and needed to remain open, if possible.

Key Facts

The Solution

The UDI process was used to stabilize the foundation.

The university contacted Groundworks to asses Henn Mansion’s foundation issues. After careful evaluation, the polyurethane injections process was selected to stabilize the foundation, as it is ideally suited to fill voids, stabilize soils below various foundation types, and lift foundations when required. Groundworks informed university officials that the building could remain open for business during the scheduled repairs.

The Impact

Groundworks successfully restored the soil’s ability to support the structure’s continuous footing.

Groundworks successfully restored the soil’s ability to support the structure’s continuous footing. During the repair, lasers sensitive to 1mm of movement were attached to the building. When movement was registered by the lasers, injection ceased as the soil was now sufficiently densified to support the load of the structure’s southeast corner, and to prevent the exterior ladder cracks from stretching further. The repair was completed in less than 48 hours. Groundworks’ repair process was quick, clean, caused little to no disruption, and most importantly helped save the historical building in its original state.