Home addition cost in Toronto typically ranges from $40,000 for a small three-season sunroom up to $800,000+ for a full second-storey addition with multiple bedrooms and a primary ensuite. Most rear additions in 2026 land between $150,000 and $400,000 for the construction work, plus permit, engineering and design fees.
Cost by Addition Type
| Addition type | Cost range | Per sq ft |
|---|---|---|
| Three-season sunroom | $40,000 to $80,000 | $300 to $450 per sq ft |
| Bump-out (50 to 100 sq ft) | $50,000 to $120,000 | $700 to $1,200 per sq ft |
| One-storey rear addition (200 to 400 sq ft) | $150,000 to $350,000 | $500 to $750 per sq ft |
| Two-storey rear addition (400 to 800 sq ft) | $300,000 to $700,000 | $500 to $700 per sq ft |
| Dormer addition (150 to 300 sq ft) | $150,000 to $300,000 | $700 to $1,000 per sq ft |
| Full second-storey addition (800 to 1,200 sq ft) | $400,000 to $800,000 | $450 to $700 per sq ft |
| Garage conversion or above-garage addition | $150,000 to $300,000 | $500 to $700 per sq ft |
Cost by Component
For a typical 400 sq ft one-storey rear addition with a kitchen, breakdown roughly looks like:
- Excavation and disposal: $8,000 to $14,000
- Foundation (concrete footings and walls): $25,000 to $45,000
- Framing, sheathing, roofing: $35,000 to $55,000
- Windows and exterior doors: $8,000 to $20,000
- Exterior cladding (brick, stone, siding): $15,000 to $30,000
- Insulation and air sealing: $5,000 to $10,000
- Plumbing rough-in: $4,000 to $9,000
- Electrical rough-in: $5,000 to $10,000
- HVAC extension or new system: $6,000 to $15,000
- Drywall and trim: $7,000 to $12,000
- Flooring: $4,000 to $10,000
- Kitchen finishes if applicable: $35,000 to $60,000
- Paint, fixtures, hardware: $4,000 to $8,000
- Tie-in to existing home (wall removal, roof tie-in, drywall patch): $8,000 to $20,000
- Project management and overhead: 15 to 25 percent of project cost
Permit, Engineering and Design Costs
- City of Toronto building permit: $4 to $7 per sq ft of new space
- Architectural drawings: $5,000 to $15,000
- Structural engineering: $3,500 to $9,000
- Mechanical engineering (if HVAC redesign): $1,500 to $4,000
- Committee of Adjustment minor variance (if needed): $1,200 to $1,800 plus 12 to 20 weeks of timeline
- Survey: $1,000 to $2,500
Toronto Labour Rates That Drive Cost
Toronto labour rates for major trades in 2026:
- Carpenter: $65 to $90 per hour
- Electrician: $90 to $130 per hour
- Plumber: $95 to $140 per hour
- HVAC technician: $90 to $130 per hour
- Tile setter: $70 to $100 per hour or $12 to $20 per sq ft installed
- Drywaller: $55 to $80 per hour
- Roofer: $80 to $120 per hour
These rates run higher than smaller Ontario markets and roughly match other major Canadian cities. Toronto labour shortages in framing and roofing also push timelines, which has its own cost effect.
How to Reduce Home Addition Cost
- Avoid wet rooms in the addition where possible (no kitchen or bathroom adds)
- Match the existing exterior cladding to skip a custom-match line item
- Stay within zoning to avoid Committee of Adjustment
- Pick mid-range cabinets and finishes; the addition is the wrap, not the show
- Avoid moving the staircase
Reference Sources
For Toronto permit fee details, see the City of Toronto building permits page. For Ontario structural and code requirements, see the Ontario Building Code.