Case Studies

Concrete Lifting and Leveling Case Studies: Marguérite Bourgeoys School Board

Wednesday, June 27th, 2018 by Gus Masoud


Project: Lift, level, and stabilize a concrete slab of approximately 1730 square feet.

Installer:  PURLIFT INC.

Challenge: The Boileau School had experienced floor settlement of approximately four inches in two classrooms, as well as a supply room.  The drop in the slabs was a result of the structure having been built on organic matter that had decomposed over time. There was also a void between the slab and the substrate of approximately two inches. Complicating matters was the fact that there were actually two slabs, sandwiched one atop the other, that had been poured separately, with a void between the two slabs and another beneath the lower level slab. As the school has a significant number of students confined to wheelchairs, the sloping floor was exceedingly problematic.


Findings: To resolve the slab settlement issue, the engineering firm of CIMA Plus and the architectural firm of Rubin Rotman Associés opted to recommend the process of polyurethane injection, as installed by Purlift Inc.

PolyLEVEL®, a high density two-part urethane that expands into a rigid, waterproof foam, and is used to fill voids, stabilize and lift concrete slabs was utilized for this project. The PL250 foam has a compressive strength of 75 pounds per square inch (psi) and provides the necessary strength to support extremely heavy loads. In addition to being hydrophobic (waterproof), it typically has an in-place weight of only four pounds per cubic foot, thus not heavy enough to add significant weight to burden an already-distressed substrate.

Results: The slab was pierced every 3’-5’ and the material, injected in a liquid state, infiltrated crevices as small as 1/32”, thus filling the void and lifting the slab to its original position. The slab elevation was continuously monitored with laser levelling equipment in order to achieve the desired outcome. The work was completed over the course of three days.

Project Summary

Project Engineer: CIMA Plus.: Certified PolyLEVEL Installer: Purlift Inc

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