Home Addition Costs in Toronto (2026): Rear, Second-Storey and Garage Additions
If you love your neighbourhood but need more space, an addition is often the better move. Here’s what home additions cost in Toronto and the GTA in 2026, what drives the price and how long the process takes, from the additions we design and build.
Short answer: full-service additions start from about $275 per square foot for a rear or ground-floor addition and about $325 per square foot for a second storey, before HST, including design, engineering drawings and permits. A 300 sq ft family-room addition usually lands between about $85,000 and $150,000. Try our renovation cost estimator →
Home Addition Cost by Type and Finish Level
Rear or ground-floor addition: about $275–$350 per sq ft (quality), $350–$425 (premium), $425–$500 or more (luxury)
Second-storey addition: about $325–$400 per sq ft (quality), $400–$475 (premium), $475–$550 or more (luxury)
These ranges include design, engineering drawings, permits, licensed trades and a dedicated project manager. Kitchens and bathrooms inside an addition cost more per square foot than bedrooms or family rooms because of the plumbing, cabinetry and tile.
Types of Additions
Rear additions: the most common way to add a bigger kitchen, a family room or a main-floor bedroom.
Second-storey additions: add bedrooms and bathrooms without using any yard space.
Over-the-garage additions: a cost-effective way to add a bedroom, office or suite on an existing footprint.
Garage additions: new attached garages, often with living space above.
What Drives the Cost
Foundation: a full basement under a rear addition costs more than a crawlspace or slab, but adds usable space.
Structure: a second storey needs the existing walls and foundation checked by an engineer, and sometimes reinforced.
Roof tie-in and exterior: matching your existing brick, siding and roof lines takes care and adds cost.
Mechanical systems: your furnace, air conditioning and electrical service may need upgrading to handle the new space.
Plumbing: adding a bathroom or kitchen in the addition adds trade work.
Zoning: if the plan needs a minor variance, the Committee of Adjustment adds time and fees.
Site access: tight lots and laneways make deliveries and excavation slower.
How Long an Addition Takes
Design, drawings and permits: about 2 to 4 months, longer if a minor variance is needed.
Construction: about 4 to 8 months, depending on size and finishes.
Your project manager gives you a schedule before work starts and keeps you updated every week, so you always know what’s next.
Can You Live at Home During an Addition?
For most rear additions, yes: the new space is built outside the existing walls and only opened into the house near the end. A second-storey addition is different, because the roof comes off for part of the build, so many families plan to stay elsewhere for some of that time. We plan the schedule and living arrangements with you before work starts.
Adding On vs Moving
Moving in the GTA comes with big costs that don’t add any space: land transfer tax (in Toronto, both provincial and municipal), realtor commissions, legal fees and moving costs. An addition puts that money into your own home instead, and lets you stay in the neighbourhood, schools and community you already love.
Permits and Approvals
Every addition needs a building permit, and many need zoning approval too. Drawings and engineering come first, then the permit application, then inspections at each stage of construction. See our renovation permit guide for how the process works.
Frequently Asked Questions
Do you handle the drawings and permits?
Yes. Design, engineering drawings and permits are included in our addition pricing, and we book the inspections and close the permit at the end.
Is a second storey cheaper than a rear addition?
Per square foot it usually costs more, because of the structural work and roof. But it adds space without using your yard, and on small lots it may be the only option.
How big can my addition be?
Zoning sets the limits: setbacks from your lot lines, height and lot coverage. We check them on your lot before design starts.
Can you add a basement under a rear addition?
Often, yes. It costs more than a crawlspace, but it adds usable space for storage, a rec room or a future suite.
Planning an Addition?
Start with a quick call at no cost. Our in-person consultation is $199, credited in full toward your project, and includes a measured floor plan of your home. See our home additions page, request a consultation or call (416) 824-8825.
