The Problem

The homeowners of this century-old heritage detached property in Toronto’s historic Annex neighborhood faced a critical issue: inadequate sub-grade vertical clearance. The existing rubble masonry foundation created a cramped, low-ceiling environment that was unusable for modern living. Furthermore, soil analysis indicated minor historic settlement. Simply digging out the floor was not an option, as removing the earth would eliminate the lateral support of the ancient foundation, risking catastrophic structural failure.

Our Professional Assessment

Our structural engineering inspection revealed that the existing footings were exceptionally shallow and lacked modern reinforcement, a common structural hurdle for heritage homes in The Annex. To safely achieve the targeted depth increase, continuous trenching was structurally unviable. Instead, the site required a highly controlled sequential excavation protocol to extend the foundation downward while ensuring the load-bearing masonry remained entirely supported throughout the process.

This strict mathematical sequencing approach allowed us to safely increase vertical clearance while preparing the sub-grade envelope for modern moisture control.

The Solution We Recommended

We engineered a comprehensive structural plan to safely execute a floor-drop and reinforce the heritage property:

  • Sequential Excavation & Shoring: Divided the foundation perimeter into mathematically controlled sections (pins). We excavated beneath the existing walls in alternating phases while installing temporary steel shoring to safely distribute the house load.
  • Foundation Extension: Poured high-MPa reinforced concrete to extend the footings downward. We utilized non-shrink dry pack grout to create a solid load transfer between the old rubble foundation and the new concrete base, strictly adhering to Ontario Building Code standards for load-bearing masonry.
  • Water Management: Installed an interior weeping tile perimeter and a heavy-duty sump pump system to manage hydrostatic pressure at the new, deeper elevation.
  • New Slab: Poured a fresh, level concrete floor engineered for long-term stability and optimal load distribution.

By combining meticulous structural excavation with advanced water management, we ensured the heritage home remained stable and secure without compromising its exterior architectural integrity.

The Results

  • Vertical Clearance Achieved: Transformed a cramped, unusable sub-grade space into a fully functional area with maximum structural headroom.
  • Structural Stabilization: The heritage home now rests on a modernized, reinforced concrete sub-structure, effectively halting historic settlement.
  • Dry & Protected: The property is fully encapsulated with a brand-new interior waterproofing envelope.
  • Preserved Integrity: Achieved significant vertical expansion with zero alteration to the home’s historic above-ground brickwork.

The homeowners now benefit from an expansive, structurally sound lower level that drastically increases the property’s footprint and market value.

Planning a depth increase for your heritage home? Contact us today to discuss your structural foundation support requirements and learn more about our floor-drop excavation techniques.

Watch The Project Video