"How much does a home addition cost?" has no single answer, because a bump-out and a full second storey are completely different projects. The type of addition drives the price far more than the square footage does. Here's the 2026 breakdown by type across Toronto and the GTA, so you can budget for the addition you're actually planning.
Home addition cost by type (GTA, 2026)
| Addition type | Per sq ft | Typical total |
|---|---|---|
| Bump-out | $85 – $200 | $5,000 – $35,000 |
| Garage addition / conversion | $90 – $140 | Varies by size |
| Dormer | $80 – $200 | Small footprint |
| Rear addition (400–600 sq ft) | $200 – $500 | $150,000 – $300,000 |
| Second-storey addition | $400 – $700 | $250,000 – $650,000 |
Across all types, GTA home additions run roughly $230–$633 per square foot in 2026, averaging around $402 per square foot. One critical note: those are usually hard construction figures. Expect total all-in cost (soft costs + HST) to run 30–40% higher, and set aside 10–20% of the budget for permits, architectural, and engineering fees.
Why the type matters so much
Bump-outs are the cheapest because they reuse the existing foundation, roof overhang, and often the room's plumbing and electrical. A small kitchen or bathroom bump-out can land in the $5,000–$35,000 range — the best value in the addition world when a few extra feet is all you need.
Rear additions add a full room (or rooms) at ground level and need a new foundation for the extended area, which is why they jump to $200–$500 per square foot. A quality 400–600 sq ft rear addition typically runs $150,000–$300,000 in hard costs.
Second-storey additions are the most involved — you're reinforcing the existing structure, removing the roof, tying in mechanicals, and usually navigating a minor variance. That puts them at the top of the range, $250,000–$650,000+ fully finished.
Garage conversions add livable space at a moderate cost but tend to offer lower resale ROI than other additions — worth it for the livability, less so purely as an investment.
What drives your number within the range
- Foundation work — a new foundation (rear addition) or reinforcing an existing one (second storey) is a major line.
- Structural complexity — cutting into load-bearing walls, new beams, and tie-ins.
- Finish level — the same as any renovation, finishes swing the total significantly.
- Permits and variances — if the design needs a minor variance, add time and cost at the front.
- Neighbourhood — labour and site access vary across the GTA.
Which addition adds the most value?
Additions that create bedrooms and bathrooms (second storeys) or open main-floor living (rear additions) tend to return the most at resale, because they address what GTA buyers actually pay for. Bump-outs are efficient for function; garage conversions add livability more than market value. The right choice is the one that fits how you live and holds its value.
FAQ
How much does a home addition cost in the GTA in 2026? Roughly $230–$633 per square foot depending on type, averaging about $402 — with all-in costs running 30–40% above the hard-cost figure once soft costs and HST are added.
What's the cheapest type of addition? A bump-out, at $85–$200 per square foot, because it reuses the existing foundation and roof.
How much is a rear addition in Toronto? A 400–600 sq ft rear addition typically runs $150,000–$300,000 in hard construction costs.
Do I need to budget for more than construction? Yes — add 10–20% for permits and design, and expect all-in costs (with HST) 30–40% above the hard-cost number.
Planning an addition? We'll help you pick the type that fits your lot and budget. See our home additions service, compare up vs. out in our addition vs extension guide, or get a free estimate.