How Much Does a Home Addition Cost in the GTA?
2026-07-20 · Colombia Construction
A home addition is often the highest-value project you can do to a GTA home, and also one of the widest-ranging on price. Here is what actually determines the number.
Home addition cost (GTA 2026)
| Type | Typical cost |
|---|---|
| Per square foot (Toronto) | $400 – $650+ |
| Rear ground-floor extension | $150,000 – $300,000 |
| Full second-storey addition | $250,000 – $450,000 |
Typical Greater Toronto Area ranges (2026), for planning only. Every project is quoted on-site.
Additions are priced by complexity, not just size
A single-room rear extension on a slab is a very different project from a full second-storey addition that requires temporary weatherproofing, structural reinforcement of the existing home and matching the roofline. Foundation work, structural engineering, and how much of the existing house is affected drive the budget as much as the square footage added.
The costs people forget
Beyond framing and finishes: engineered drawings and permits, connecting new HVAC, electrical and plumbing to the existing home, matching exterior materials so it does not look bolted on, and the weather-tight envelope that survives GTA winters. Budgeting for these up front is what separates a smooth addition from a stalled one.
Ready for a quote? See Home Renovations or home renovations in Mississauga — serving the GTA.
Related guides
- Planning a Home Addition in the GTA: What to Know First
- Toronto Second-Storey Addition Costs
- Home Renovation Timeline in Toronto