If you're planning a house extension in Toronto—say expanding your kitchen, adding a second-storey, or building out to fit a growing family—this article will walk you through what it costs, why costs vary, how to budget, and how to maximise value. It is tailored with Canadian English, local market context, and practical tips for the City of Toronto area.
Here are current ballparks for home extensions in Toronto (2025) based on recent industry sources:
Basic home additions (standard finishes, less complexity) are generally in the range of CAD $350-$400 per sq ft.
Mid-range additions (upgraded materials, some complexity) often run $400-$500 per sq ft.
High-end or complex additions (luxury finishes, structural modifications, custom design) can exceed $550+ per sq ft.
To give an example: many full home additions in Toronto are quoted between $420,000 and $820,000 including taxes for a typical project size.
So if you’re thinking of adding, say, 400 sq ft of space with standard finishes, you’d be looking at somewhere around $140,000-$160,000 (400 × $350-$400). For higher end, same size could be $220,000+.
There are multiple variables that influence the final cost of a house extension in Toronto. Knowing these helps in both realistic budgeting and making cost-effective choices.
2.1 Size & Scope
Larger additions can benefit from some economy of scale (cost per sq ft can drop slightly) but the total cost is higher.
A simple single-room extension differs greatly from a full second-storey or complex integration with existing house.
2.2 Type of Addition & Structural Requirements
A ground-floor room versus a second storey: second storey often requires reinforcing foundations, structural modifications, staircases, etc., which adds cost.
Foundations, piles, or slab work also vary in cost. For example: additions built on a full foundation/slab may cost more than on piles because of excavation and insulation implications.
2.3 Materials & Finishes
Standard materials (drywall, standard windows, good but not premium finishes) are on the lower side of the range.
High-end materials (custom cabinetry, stone, high-performance windows, luxury flooring) push costs up significantly.
2.4 Labour, Contractor & Location Specifics
Toronto’s labour market and site constraints (tight lots, older homes, limited access) can increase costs.
Contractor experience, scheduling, and seasonal demand can also affect price.
2.5 Permits, Professional Fees & Regulations
Permits and code compliance matter. In Toronto you must heed zoning, by-law setbacks, heritage overlay (if any), and building permits.
Architectural/engineering fees: often a portion of the total budget.
Unexpected structural issues (e.g., hidden damage, soil issues) often raise costs—so contingency is recommended.
2.6 Site Conditions & Access
Older homes, difficult access, limited staging space, neighbours, excavation for basement or second-storey all add cost.
Here are a few typical scenarios in Toronto to illustrate:
Single-storey horizontal extension (e.g., new family room or expanded kitchen)
Suppose 300 sq ft, standard finish: at $350-$400/sq ft → ~$105K-$120K plus permits/professional fees/contingency.
Mid-range kitchen extension + new dining area, 400 sq ft
At $400-$500/sq ft → ~$160K-$200K. Materials and finishes will lean higher (kitchen cabinetry, appliances, finishes).
Second-storey addition
Because foundation/structure work is required, cost per sq ft might be higher (~$450-$550+). So for 1,000 sq ft you might be looking at ~$450K-$550K+. Some sources list $300-$360/sq ft for second story in certain cases but that tends to assume minimal reinforcement.
Luxury/custom addition
Could go $600/sq ft+ easily if you’re doing multiple rooms, custom design, premium finishes.
Given the variability, here are some practical budgeting considerations:
Set aside contingency: 10-20% of your budget is wise for unforeseen conditions.
Obtain multiple quotes: Compare not just price but scope, materials, timelines.
Define finish level early: Materials/finishes make a big difference; decide early.
Confirm permits/zoning early: Unexpected delays or requirement changes add cost.
Break project into distinct phases: Demolition/structural first; finishes later.
Consider living arrangements during construction: If major work, you may need alternate accommodation which adds cost.
Evaluate return on investment (ROI): While extensions add space/value, cost should align with expected value increase in your neighbourhood.
Stick to your scope: “Change orders” during construction are a common cost driver.
Extensions in Toronto not only increase livable space but can boost resale value—especially in tight-lot older neighbourhoods where moving is difficult.
But ROI depends on neighbourhood, market conditions, quality of finish, and how seamlessly the addition integrates with the existing home.
Overbuilding (in finish level or size) relative to neighbourhood norms may not always see full cost recovery.
Many homes in Toronto have limited lot coverage or narrow side-yards—zoning and by-law requirements (setbacks, lot coverage, height limits) may restrict what you can do.
Older homes may require structural upgrades (foundation, crawlspace, roof) when you attach an extension—this can add cost.
Infrastructure: in-home services (electrical, HVAC, plumbing) may require upgrade if you expand significantly.
Heritage or conservation zones: additional restrictions and costs may apply.
Seasonal and contractor availability: Toronto’s busy construction market may mean longer lead times or higher labour costs.
Average cost per sq ft for a house extension in Toronto in 2025: $350-$500 for standard to mid-range work; high-end projects exceed $550+.
A full addition (hundreds of square feet) often costs $200K-$600K+, depending on size, complexity, materials.
Major cost drivers: size/scope, structural requirements, material/finish level, labour/site conditions, permits & design fees.
Set a realistic budget including contingency, engage experienced professionals early (architect/engineer/contractor), define finish level clearly, and verify zoning & permit path.
With good planning, an extension can be one of the most effective ways to increase both living space and property value in Toronto—especially when moving isn’t an appealing option.