9″ Floor Lift

Boston, MA


The floating slab floor of a flex space building in Boston, Massachusetts settled up to 9 inches. The tenant was approaching renewal and had mentioned that the floor settlement was affecting the usability of their space.

The tenant was an environmental testing company for ships entering the Port of Boston. Daytime staffing levels were high, but there were also continuous nighttime operations to service incoming cargo shipments. The tenant made it clear to the building owner that operations could not be affected at all by any floor repairs.


CJGeo proposed polyurethane grouting using plural component TerraThane to fill voids below the floor and then raise it back to flat. The floor slab settlement resulted from backfill consolidation after building pad preparation. The finished floor elevation was roughly 5′ above the adjacent parking lot, which was at original grade.  

Since polyurethane grout is significantly lighter than cement-based grouts (4lb/cuft vs 130lb/cuft), using polyurethane grout helps reduce chances of resettlement from applying additional burden on top of the backfill material.

Polyurethane grouting is also exceptionally clean; injection holes are just 5/8″ diameter, dustless drilling is used, and the process is very quiet. This facilitates work in occupied facilities with minimal disruption. All raw material is contained in CJGeo’s trucks, with no concrete truck deliveries, which also allows for easy scheduling of night work or other special schedules around tenant needs.


CJGeo mobilized a two-pump polyurethane grouting truck to the site. The first shift was daytime work and corrected the worst areas of settlement in the warehouse area. The following night, the second and final shift of work was done to correct settlement in the office areas which were unoccupied at night.

The repair was successfully completed with no disruption to the tenant, and the slab was restored to level.