Situation
A century-old two-storey semi-detached residential building in downtown Toronto was proposed to be converted into a three-storey modern residence with a full basement. To meet the City’s renovation classification requirements, the project was defined as a major renovation rather than a new build, requiring retention of the existing side walls.
The existing structure consisted of shallow stone footings, 2x4 wood framing, and unreinforced masonry elements, presenting significant structural and constructability challenges.
Engineering Scope
Engaged as the structural engineer of record, services included assessment of the existing structure, development of staged construction and temporary support strategies, and design of permanent structural upgrades to support the new configuration.
The scope included foundation underpinning, reinforcement of existing load-bearing walls, structural separation from the adjoining semi-detached building, and design of new wood framing and steel framing to support modern architectural forms. The project also included structural design for a new laneway suite constructed as a separate new-build structure on the property, along with periodic site visits during construction.
Key Engineering Considerations
Underpinning of existing stone foundations to accommodate a new basement
Reinforcement of existing wood framing to support additional storeys and loads
Structural separation of the semi-detached building to create an independent load path
Temporary shoring and support of the existing structure during construction
Stabilization and sequencing around an unstable masonry chimney
Integration of steel framing to support contemporary architectural arches and geometries
Coordination with architectural design intent and construction constraints
Outcome
A comprehensive structural design was developed and implemented, addressing the challenges associated with upgrading a historic structure while maintaining compliance with renovation requirements. The project successfully transformed the existing building into a three-storey luxury residence with a basement, while preserving required elements of the original structure.
The final design resolved complex load path, sequencing, and constructability issues, and played a key role in shaping the completed multi-million-dollar residential development.
Projects involving major renovations to older Toronto homes highlight the importance of working with a licensed structural engineer in Toronto who understands permitting classifications, load-path continuity, and staged construction in constrained urban conditions.
Related Engineering Services
Discuss a Similar Engineering Challenge
If you’re planning a project with similar structural constraints or technical challenges, we can provide practical engineering guidance and documentation. Contact a structural engineer.