Engineering Heritage: Integrating North America's Largest Façade Retention System with Support of Excavation in the United Bldg. Project-Video

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Mark Reinders of Green Infrastructure Partners presented the construction of North America’s largest facade retention system, integrated with support of excavation, for a downtown Toronto condominium project. Two heritage buildings—the former birthplace of McLean Publishing—had to remain intact while a 50-storey development and underground parking garage were built.<br /><br />The project reused and reinforced the buildings’ existing structure, then transferred their estimated 20,000-tonne load onto exterior secant piles and micropiles and 16 interior king piles. A carefully monitored, five-stage jacking and column-cutting process shifted the load safely onto the new support system. Excavation began in 2023, with shotcrete panels replacing difficult-to-install interior walers and helping keep work on schedule.<br /><br />The excavation reached bedrock in December 2023, with monitored movements remaining acceptable. The facades stayed intact throughout construction, and the new superstructure was ultimately tied into the existing buildings. Reinders credited close collaboration among the owner, contractors, engineers, and suppliers for the project’s success.

Keywords

facade retention system

Toronto condominium project

heritage building preservation

support of excavation

micropiles and secant piles