Before you start planning your Ottawa home addition, it’s important to understand the costs involved. This will help you create a realistic budget for the size and scope of the addition you have planned. Below you’ll find a breakdown of the average costs of different additions and extensions as well as useful information such as the ROI of additions and prices for various room sizes.
Disclaimer:
The costs listed in this guide are average prices provided for educational purposes only, based on market data available at the time of publication in 2025. Actual costs for your home addition may vary depending on the specific details of your project, materials chosen, and current market conditions. Each home addition is unique. For an accurate, customized estimate for your home addition project in Ottawa, please contact Select Urban General Contractors directly.
Breakdown of Home Addition Costs in Ottawa
Every home addition has unique elements. For example, second-storey additions require stairs, windows, and new electrical wiring, whereas bathroom addition needs plumbing fixtures and systems. As a result, the cost of each addition varies. The following chart includes the average cost of additions and extensions in Ottawa:
Type of Addition | Average Cost |
|---|---|
Single Room Addition | $50,000 to $100,000 |
Bathroom Addition | $30,000 to $75,000 |
Kitchen Addition | $75,000 to $150,000 |
Second-Storey Addition | $250,000 to $500,000+ |
Sunroom Addition | $25,000 to $70,000 |
Deck/Patio Addition | $15,000 to $50,000 |
Single-Car Garage Addition | $50,000 to $90,000 |
Two-Car Garage Addition | $100,000 to $120,000 |
Attic Conversion | $50,000 to $120,000 |
The figures above can change depending on the size of the addition and customized features. To receive an accurate estimate, it’s best to consult with a reputable contractor. Schedule your free in-home consultation with Select Urban General Contractors today. Call us to book!
What Is the ROI of a Home Extension?
The return on investment (ROI) of your addition is a key consideration for future planning. The ROI is different for every type of addition. On average, house additions recoup 50% to 60% of the total cost. However, there are a few additions that can recoup even more. This includes kitchen and bathroom addition, which have an average ROI of 75% to 85%. Second-storey additions are another high ROI renovation, recovering 65% to 80%. This means that if you decide to sell, you could recover more than half of your expenditure. In addition to the project scope, a few factors that alter ROI are location, current market conditions, inclusion of energy-efficient upgrades, and quality of the workmanship.
What Impacts the Cost of Home Additions?
There are a variety of factors that influence the cost of home additions, including size, materials, finishes, labour, and project fees. Here’s a closer look at each factor:
Addition/Extension Size
The larger the addition or extension, the more materials and labour are required. This increases the overall costs. However, large additions with basic designs and without any customization can cost less than smaller additions that include customized high-end finishes, premium materials, and luxury features.
Materials & Finishes
The quality and quantity of the materials used in your addition affect costs. This includes cabinetry, windows, and doors. The types of finishes can also increase or decrease the final price of your addition or extension. This includes interior finishes such as flooring and wall paint as well as exterior finishes such as stone, brick, or vinyl siding.
Labour Expenses
The professionals involved in the addition, including carpenters, electricians, plumbers, architects, and engineers, may have varying rates and fees associated with their services. Labour costs are also influenced by skill level. Experienced professionals, especially those with specialized skills, often have higher fees reflecting their reputation and expertise.
Project Fees
There are certain aspects of a home addition that come with fees on top of the design and construction costs. These include fees for permits, inspections, architectural services, and engineering services. This will vary from one project to another based on the contractors you work with and the type of addition you’re planning.
How Much Does It Cost to Extend a House?
Typically, home extension costs in Ottawa cost $150 to $500+ per square foot. Extensions you may be interested in include kitchen extensions, rear hoe extensions, master bedroom extensions, and bump outs. Extensions that require a significant amount of structural work or involve plumbing, drainage, and electrical systems can be more expensive. Here’s a chart outlining different extension costs:
Type of Addition | Average Cost |
|---|---|
Single Room Addition | $50,000 to $100,000 |
Bathroom Addition | $30,000 to $75,000 |
Kitchen Addition | $75,000 to $150,000 |
Second-Storey Addition | $250,000 to $500,000+ |
What Is the Cost to Add a Second Floor Ontario?
On average, adding a second-storey addition to your home in Ontario costs between $350 and $400+ per square foot. However, this price range fluctuates based on the exact project specifications. The amount and types of rooms you include in the addition can have a major impact on the final cost. For example, adding one bedroom versus four bedroom or an ensuite versus two three-piece bathrooms. Furthermore, any add features for hobby rooms will also alter costs. As an example, if you include a movie room in the addition, you might also add a wet bar and soundproofed walls. Here are some of the cost-related factors to consider during a second-storey addition:
Start Planning Wisely–Book Your Consultation for Your Home Addition in Ottawa
Start your Ottawa home addition off right with the help of Select Urban General Contractors. We’re an experienced team that’s trusted throughout Ottawa. We specialize in all types of home additions and renovations. No projects too big, too small, or too complex for us! Call us today and schedule a complimentary consultation to learn more about our services and how we can help build your dream addition.