What's the per-sq-ft cost for a two-storey Toronto addition?

Two-storey additions in Toronto typically run $350–$550+ per square foot for the addition's footprint, though the all-in cost depends heavily on finishes, complexity, and site conditions.

To clarify how the math works: that per-square-foot figure is usually calculated on the ground floor footprint of the addition, not the total combined square footage of both floors. So a 400 sq ft footprint gives you 800 sq ft of new living space, but you'd price it as 400 sq ft at the higher rate — because you're still building one foundation, one roof, and all the structural framing for two floors.

Here's a realistic breakdown of where projects land in the Toronto market:

• Entry-level ($350–$400/sq ft): Standard finishes, straightforward site access, simple roofline tie-in, no major structural complications
• Mid-range ($400–$475/sq ft): Better finishes, some custom millwork, more complex integration with the existing home
• Premium ($475–$550+/sq ft): High-end finishes, complex rooflines, heritage home integration, difficult lot access, or significant structural upgrades to the existing structure

What drives the cost up in Toronto specifically is the integration work — tying the new addition into an existing home is almost always more expensive than new construction. Expect costs for underpinning or reinforcing the existing foundation, upgrading your electrical panel (very common in older Toronto homes), and rerouting HVAC to serve the new space. Homes in older neighbourhoods like The Annex, Leslieville, or Cabbagetown often carry a premium due to heritage considerations and aging infrastructure.

Toronto Permits and Timelines

A two-storey addition requires a building permit from the City of Toronto Building Division (416-397-5330 or toronto.ca/building). Budget $2,000–$6,000+ for permit fees depending on the project value, and allow 6–12 weeks for permit approval on a project this size. If your addition pushes setback or lot coverage limits, you may need a Committee of Adjustment variance, which adds 3–4 months to your timeline. Start this process early — it's one of the most common project delays in Toronto.

What's Typically Not Included

The per-square-foot number from most contractors won't include landscaping restoration, driveway repairs, window coverings, furniture, or HST. Always confirm what's in scope. HST alone adds 13% to your contract value, which surprises some homeowners.

The honest answer is that you won't get a reliable number without a site visit and drawings. Two additions that look identical on paper can differ by $80,000+ depending on what's discovered once a contractor opens up the existing walls. Get at least three quotes from licensed general contractors, and make sure each quote is based on the same scope and drawings.

Browse licensed general contractors in our directory at the Toronto Construction Network to find professionals who regularly work on Toronto additions and understand local permit requirements.