In 2026, a Toronto home addition typically costs about $300 to $360 per square foot, while complex second-storey additions may reach $400 to $500 per square foot. That puts a 1,000-square-foot addition at roughly $300,000 to $360,000. Your final budget will depend on the addition type, structural work, ceiling height, site access, permits, and material selections. Planning the design and scope early helps you understand where the money goes and reduces expensive changes once construction has started at your property.
Average Home Addition Cost in Toronto per Square Foot
Home additions in Toronto typically range from about $400 to $500 per square foot. This provides a useful starting point for early budgeting, but it is not a fixed construction quote. The final rate will depend on the addition type, existing home, design requirements, site conditions, and selected materials.
| Addition Size | At $400/sq. ft. | At $500/sq. ft. | Estimated Construction Range |
|---|---|---|---|
| 200 sq. ft. | $80,000 | $100,000 | $80,000–$100,000 |
| 300 sq. ft. | $120,000 | $150,000 | $120,000–$150,000 |
| 500 sq. ft. | $200,000 | $250,000 | $200,000–$250,000 |
| 750 sq. ft. | $300,000 | $375,000 | $300,000–$375,000 |
| 1,000 sq. ft. | $400,000 | $500,000 | $400,000–$500,000 |
The price per square foot can change significantly between projects. A first-floor extension may require excavation and a new foundation, while a second-storey addition often involves structural reinforcement and roof removal. Adding a kitchen or bathroom increases plumbing, electrical, HVAC, cabinetry, and fixture costs. Design complexity, window sizes, exterior materials, interior finish level, property access, and the condition of the existing house also affect pricing.
The $400–$500-per-square-foot figure should not automatically be treated as the complete project budget. Design, engineering, permits, demolition, landscaping or restoration, HST, and a contingency allowance may need to be budgeted separately, depending on the builder’s contract and listed exclusions.
Home Addition Cost by Type in Toronto
Home addition costs in Toronto vary by project type, as each option has different structural, foundation, mechanical, and finishing requirements.
Cost of Adding a Second Story
Adding a second story to your home is a good way to increase your home’s square footage without taking up additional land. Homeowners who don’t have the land capacity to expand their home horizontally can extend vertically.
Plus, two-story homes perform better on the market. So if you plan to sell your home at some point, having a second story works to your advantage. The cost of adding a second story in Toronto is between $300-$360 per square foot. So depending on the size, the cost will fluctuate.
Planning a second-story addition takes a few months. The structural integrity of the home will be critical in determining whether such an addition is feasible and safe. If there are no delays, a turnkey second-story addition can take about three months to complete. Be sure to acquire the necessary permits before beginning the process.
Sunroom Addition Cost
A sunroom is an excellent addition to your home. It allows you to enjoy some good Vitamin D without being exposed to weather elements. Your sunroom needs to be designed to allow for sufficient ventilation and insulation. Different construction methods are used to build sunrooms, and careful thought should go into determining which one is the best option for you. Your sunroom will either be built on a foundation, piles, or concrete slab.
Many homeowners in Toronto choose to have their sunrooms constructed on piles because it is the least costly of the three, costing between $250-$380 per square foot.
Cost to Add a Room by Room Size
The size of the new room will greatly determine the cost of the project. One of the challenges with room additions is that you don’t always know how much it will cost until the details of the project are examined.
| Room Size | Average costs of project in Toronto |
| 10×10 room addition | $12,500-$25,000 |
| 12×12 room addition | $18,000-$36,000 |
| 20×20 room addition | $50,000-$100,000 |
The Cost of Adding a Basement
There are many practical reasons why having a basement in your home is beneficial. However, it is a complicated and very costly venture. This is because the house will need to be lifted first, which costs around $40,000-$65,000, and foundational work to include the basement will be an additional $40,000-$60,000. This is in addition to the cost of finishing a basement which is about $50 per square foot. So, when all is said and done, you may spend anywhere from $150,000-$300,000.
If you already have a basement and would like to expand that space, you can do so through underpinning. The cost will vary, and it is important to note that this kind of home addition may not be suitable for every home. If the home is made of wood or some other light weighing material, then underpinning will be a lot easier to do. However, if the home has masonry covering its exterior, it will be a much more difficult and expensive process.
Cost to Convert an Attic
An attic is typically used for storage. Make this space more useful by converting it into a more functional room. The key with attic conversion is that your roof needs to be at least 7 feet above the floor of your attic for most of the surface area.
If this isn’t the case, then you’ll need to lift the roof. For example, 20×20 room addition can cost between $30-$42 per square foot. You’ll need to hire a structural engineer to make sure that the conversion is possible and can be done safely without jeopardizing the rest of the home.
How Construction Method Affects Home Addition Cost in Toronto
| Construction Type | Average Cost | Pros | Cons |
| Piles | $225-$270 | · Easier to build and uses less invasive machinery. · High ROI | · Does not offer the best insulation, so energy bills will be high during winter. |
| Concrete Slab | $265-$310 | · Offers better insulation | · Temperature fluctuations and soil settling can cause cracks. |
| Foundation | $265-$310 | · Good option if you are adding plenty of space. | · Blending the addition takes great skill. |
Factors Affecting Home Addition Costs in Toronto
Being aware of the variables that will impact the cost of your home addition in Toronto will help you plan according and get a better idea of the project’s cost.
Permits and Plans for House Extension
Before you can begin any construction work, you will need to determine what type of building permits are required for the project and obtain them from your municipality. Zoning regulations establish rules and guidelines about what types of home extensions are permitted in the area. Make sure that you know these guidelines before proceeding with your home addition plan.
Before issuing a permit, most principalities will require plans that have been drawn up by a qualified architect. How much you will need to spend on the permits depends on where you live and the nature of the home addition. On average, the cost of permits is $240. However, having an architect or professional draw up your building plans can cost anywhere from $2,400 to $4,200. In general, the plans for your project will range from 10-20% of the total cost of your home addition.
Benefits of Home Addition
Planning a Home Addition in Toronto?
Not sure which type of home addition makes the most sense for your property and budget? Aria Build can review your home, goals, and project scope to help you understand the most practical options and likely costs.