Unlocking the Toronto Fourplex: 3 Structural Challenges We Tackled On-Site Today

In collaboration with: GXGprojects

Toronto’s older housing stock is famous for its character, charm, and—let’s be honest—its ability to throw a massive curveball into your renovation budget.

Converting or upgrading a fourplex in the city is a fantastic investment, but it rarely comes without a fight from the bones of the building itself.

Today on the site, we got our hands dirty dealing with the reality of century-old architecture. Here is a breakdown of the three major structural challenges we faced on this Toronto fourplex and exactly how we are solving them.

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1 - The Foundation & Underpinning Dilemma

Like many older homes in the city, the original basement wasn't dug with modern, multi-unit living in mind. To create a legal, comfortable lower-level suite, we needed more height.

• The Challenge: Lowering the basement floor meant underpinning the existing rubble foundation. Digging too fast or without proper sequencing in these tight Toronto lots risks undermining the structural integrity of the entire building—and potentially the neighbour’s house, too.

• The Fix: We brought in our structural engineers to design a strict, staggered underpinning sequence. By excavating and pouring concrete in small, alternating sections (the classic "A-B-C" method), we are safely transferring the building's load to a deeper, reinforced concrete footing without risking a collapse.

2 - Sagging Floor Joists and "Ghost" Load-Bearing Walls

Over the last 80+ years, this property has seen its fair share of DIY renovations.

• The Challenge: Once we opened up the ceilings, we discovered that previous owners had haphazardly sliced through old-growth floor joists to run plumbing and HVAC. Worse, a crucial load-bearing wall on the main floor had been removed years ago without a proper support beam, causing the second and third floors to sag toward the center of the house.

• The Fix: We had to temporarily shore up the upper floors from the basement all the way to the roof. We are currently sistering the damaged joists with engineered lumber to restore floor rigidity, and we’re dropping in a massive steel I-beam to properly carry the load where that missing wall used to be.

3 - The Party Wall and Asymmetrical Settling

Toronto’s narrow lots often mean you are intimately connected to your neighbours, and this fourplex is no exception.

• The Challenge: The building shares a masonry party wall with the property next door. Over the decades, the two structures have settled at slightly different rates, resulting in a distinct lean and some alarming step-cracking in the brickwork along the shared load path.

• The Fix: Before we could do any heavy framing, we had to stabilize the masonry. We used helical ties to stitch the brickwork back together and reinforce the connection between the party wall and the exterior walls. It’s tedious work, but it ensures the building won't shift further once we add the weight of the new drywall, kitchens, and finishes.

The Takeaway

Renovating a Toronto fourplex is not for the faint of heart, but doing it right is what turns a risky property into a safe, high-performing asset. You can’t just cover up structural flaws with fresh paint and luxury vinyl plank—you have to fix the bones first.

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About GXGprojects

GXGprojects is an international design and architectural studio built on a simple yet ambitious idea: designing your dreams. Originating in Turin, Italy, the practice was founded through the collaboration of creative minds focused on transforming ideas into tangible, real-world solutions. Today, the studio operates across Italy and Canada, combining European design sensibility with a global perspective.

At its core, GXGprojects is more than a design service—it acts as a partner throughout the entire creative and construction journey. Each project begins with a deep understanding of the client’s lifestyle, goals, and vision. Rather than imposing a predefined style, the studio develops tailored solutions that feel personal, intentional, and grounded in real needs.

The studio offers a complete range of services, including architectural design, interiors, 3D modelling, rendering, and immersive virtual tours. Through advanced visualization tools, GXGprojects enables clients to experience spaces before they are built, turning concepts into clear and realistic visions.

Beyond design, GXGprojects supports project coordination and execution, connecting clients, contractors, and regulatory processes. This hands-on approach ensures clarity and efficiency from concept to completion, resulting in spaces that are both refined, buildable and deeply connected to those who inhabit them.