Case Study: Foundation Stabilization of a Residential Complex

A home is only as strong as its foundation. Unfortunately, at the a Pennsylvania residential complex, the foundation was sinking because of void growth beneath the concrete slab foundation which affected 4 condos and their respective second floor units. This case study will examine how Utility Services Group addressed the void growth and foundation settlement that was occurring at this complex in Pennsylvania using NCFI’s Terrathane™ 24-003. We used 24- 010 as well for lifting after stabilizing.

The Problem: Underneath the multi-residential complex, a 2” water main leaked for months. This leak resulted in the washing away of soils that support the complex’s foundation. The washing away of these support soils led to the growth of a 9” void below the foundation, which led to foundation settlement. This settlement caused problems which could be observed within the building, such as cracking in the ceiling, cracks in the walls, cracks in the concrete foundation slab, and the floor separating from the walls. If left unchecked, foundation settlement would have caused continued damage to occur within the Fairways building complex.

The Solution: Partnering with a local, forensic engineering firm and a renowned general contractor in the area, Utility Services Group accessed the complex and devised a plan to resolve the problems. The plan was to use Deep Soil Stabilization to return soil stability, fill the voids, and lift the buildings slabs back to within tolerance.

USG used 3 depth injection of NCFI’s Terrathane™ 24-003 around the perimeter of the buildings. This restored soil load bearing capacity for the footer of the building. Underneath the interior of the buildings, this same polyurethane was injected to a single depth. The 9” void was also filled with this state-of-the-art polyurethane. The 24-010 was then used to lift settled slabs, in most cases to their original grade. This project was successfully completed in a three-week timeframe.

The Results: USG successfully executed this service for the residential complex, returning the concrete slab foundation to grade. The result was a lift of up to as much as 2”. The soil and the foundation were both stabilized, ending the damage that would have continued had the foundation been left to settle.