Quick Answer: Home addition cost in Canada ranges from $80 to $650 per square foot in 2026, depending on the type. A bump-out runs $85 to $200 per square foot, a garage addition $90 to $140, a dormer $80 to $200, and a full rear addition $200 to $500. Type, size, and region drive most of the difference.
How Much Does Each Type of Home Addition Cost in Canada?
Home addition cost in Canada varies more by type than by size alone. A small bump-out can cost far less per square foot than a full rear addition, since it reuses the existing foundation and walls. Garage additions and dormers sit in between, while a complete rear expansion runs highest because it needs an entirely new foundation and roof tie-in.
Square foot cost is the clearest way to compare these projects, since the same addition can range from a $15,000 weekend-scale job to a $300,000 expansion depending on finish level. Here’s a cost breakdown for the four most common addition types built across Canada in 2026.
| Addition Type | Cost per Sq Ft (CAD) | Typical Total Cost |
|---|---|---|
| Bump-out | $85 – $200 | $5,000 – $35,000 |
| Garage addition | $90 – $140 | $37,000 – $132,000 |
| Dormer | $80 – $200 | $40,000 – $58,000 |
| Rear / full addition | $200 – $500 | $150,000 – $500,000+ |
Bump-Out Addition Cost
A bump-out extends a single room by 2 to 15 feet without a full foundation, often cantilevered straight off the existing structure. In Canada, this is the cheapest way to add space: $85 to $200 per square foot, or roughly $5,000 to $35,000 total. Kitchen and bathroom bump-outs land at the higher end because of fixture and venting work. A bedroom or living room bump-out stays closer to the low end since it usually reuses existing electrical and HVAC.
Garage Addition Cost
Building a brand new attached garage runs $90 to $140 per square foot in Canada, or about $37,000 for a single-car structure up to $132,000 for a finished two-car version. That’s different from a garage extension, which lengthens or widens an existing garage along one shared wall and typically costs less per square foot, since part of the foundation already exists. Building a second storey above a garage behaves more like a standard second-storey addition and can climb to $250 to $400 per square foot once load reinforcement is involved.
Dormer Addition Cost
A dormer adds headroom and a window to an attic or upper floor without expanding the home’s footprint. Canadian projects average close to $115 per square foot, with most homeowners spending $40,000 to $58,000 for a single dormer. Smaller shed dormers can land under $20,000, while larger or multiple dormers can run past $90,000. Roof pitch, foundation reinforcement needs, and whether the new space gets a finished interior all move the price within that range.
Rear and Full Addition Cost
A rear or full single-storey addition adds an entirely new section to the back, side, or front of the house, complete with foundation, framing, and a new roof. It’s the most expensive addition type in Canada at $200 to $500 per square foot, or $150,000 to $500,000 and up for a typical 400 to 1,000 square foot expansion. Costs trend toward the top of that range in the Greater Toronto Area, where labour and material pricing sit well above the national average.
What Factors Drive Up House Extension and Renovation Costs in Canada?
A house extension costs more per square foot than a typical renovation cost for existing space, since new construction needs its own foundation, structural engineering, and code compliance from the ground up. Beyond addition type, the biggest swings in your final number come down to permits, regional labour rates, and whether your project qualifies for federal tax relief. If you’re still weighing an addition against starting over, our guide to renovation vs. rebuild breaks down when each route makes more financial sense.
Permits, Codes, and Regional Costs
Nearly every home addition in Canada needs a municipal building permit before work starts. Provincial building codes are built on the National Building Code of Canada, which sets the baseline structural, fire, and energy requirements that provinces then adapt into their own codes, such as the Ontario Building Code. Permit fees are usually charged per square metre of new floor area plus a flat base fee, often landing between $800 and $2,000 for a mid-sized addition. Labour and material costs aren’t uniform across the country either: GTA pricing runs roughly 15% above the Canadian average because of higher trade wages and tighter lot access, so the same renovation, addition, or garden suite project costs noticeably more in Mississauga or Toronto than in a smaller Ontario town.
Financing and Tax Credits for Your Addition
Two federal programs can offset part of your renovation cost, though both come with real limits. The Multigenerational Home Renovation Tax Credit refunds 15% of up to $50,000 in qualifying expenses, capped at $7,500, when an addition creates a self-contained secondary unit for a senior or a relative eligible for the disability tax credit. The GST/HST New Housing Rebate can also apply, but only if the work counts as a major addition that at least doubles your home’s living space, such as a full second storey. A sunroom or single bedroom addition doesn’t qualify on its own, and the federal portion phases out once your home’s value passes $450,000, which rules out most GTA properties. Ontario homeowners can still claim the province’s separate portion, worth up to $24,000, regardless of that cap. For help mapping these credits against your project, see our planning and financial guidance resource.
Frequently Asked Questions
1. How much does a home addition cost per square foot in Canada?
Home addition cost in Canada in 2026 depends heavily on type:
- Bump-out: $85 to $200 per square foot
- Garage addition: $90 to $140 per square foot
- Dormer: $80 to $200 per square foot
- Rear or full addition: $200 to $500 per square foot
2. What is the difference between a garage addition and a garage extension?
A garage addition builds an entirely new attached or detached garage, costing $90 to $140 per square foot in Canada. A garage extension lengthens or widens an existing garage along a shared wall, which usually costs less per square foot because part of the foundation and framing already exists.
3. What is the cheapest type of home addition to build?
A bump-out is typically the cheapest home addition in Canada, at $85 to $200 per square foot. It reuses the existing foundation, roof overhang, and often the room’s plumbing and electrical, keeping most projects to $5,000 to $35,000, well below a full rear addition.
4. Do I need a building permit for a house extension in Canada?
Yes. Almost every house extension in Canada requires a municipal building permit before construction starts, plus compliance with your province’s building code. Permit fees vary by municipality, but they commonly run several hundred to a couple thousand dollars depending on the size of the addition.
5. Can a home addition qualify for a federal tax credit or rebate in Canada?
Possibly. The Multigenerational Home Renovation Tax Credit refunds up to $7,500 for additions that create a secondary unit for a senior or disabled relative. The GST/HST New Housing Rebate can apply too, but only to additions that at least double your home’s living space, and only below a $450,000 home value for the federal portion.
Conclusion
Home addition cost in Canada comes down to type, square footage, and region, with a simple bump-out costing a fraction of a full rear or second-storey expansion. Pair these benchmark ranges with a site-specific quote before you budget, since soil conditions, your municipality’s permit fees, and your home’s existing structure all shift the final number. If you’re planning a home addition anywhere in the GTA or across Ontario, Leedway Group’s design-build team can walk your property and turn these ranges into a fixed, code-compliant budget; browse our home renovation guides for more project-specific planning.
