A-502 Additions & New Builds
A second-storey addition engineered for the house below
A second storey adds bedrooms and bathrooms without giving up yard. In Toronto it typically costs $300 to $560 per square foot, and the existing house must be able to carry it.
- Typical cost
- $300–
$560 per sq ft - Timeline
- 3–6 months on site
- Permit
- Yes, building permit
- Prices checked
- 2026
- In-house structural engineering
- Permit drawings prepared in-house
- Free on-site estimate
Free, no-obligation estimate. We typically reply within 24 hours.
A-502.1 Why MKC
Why choose MKC for second-storey addition
Building up starts with the house you have. The roof comes off, and the footings, foundation and bearing walls below must carry a new floor, a new roof and the snow on it. Our in-house engineering department assesses the structure, designs any reinforcement and prepares the permit drawings, and the same company builds it. Zoning is checked first: height, setbacks and floor area. We only use ECRA/ESA-licensed electrical contractors to perform any electrical work.
The structure is checked before design
A second floor adds load to walls and footings that were sized for one storey. Our engineers open up and measure what is there, then specify the beams, posts and footing upgrades the new floor needs. That cost is in your estimate before the roof comes off, not found halfway through.
A-502.2 Scope
What’s included
- A-502.1Full second storeyA new floor over the whole house, with bedrooms, bathrooms and a new roof.
- A-502.2Partial second storeyA new level over part of the house or the garage, tied into the existing roof.
- A-502.3Structural reinforcementBeams, posts and footing upgrades so the existing house carries the new floor.
- A-502.4New stair and layoutA stair built to the Ontario Building Code, with the ground floor replanned around it.
- A-502.5Heating, plumbing, electricalServices extended upstairs by the licensed trades each one requires, with inspections.
- A-502.6Zoning, drawings, permitsZoning review, minor variance drawings, engineering and the permit application.
A-502.3 Cost guide
What it costs
in Toronto & the GTA
Published 2026 Toronto prices for a finished second storey on an existing house, from a standard fit-out to mid-range work.
Finished second storey on an existing house, standard to mid-range finish
Allow two to four months for design, engineering and drawings, and longer if a minor variance is needed. Toronto reviews complete house permit applications within 10 business days. Construction usually takes three to six months, and most families live elsewhere while the roof is off.
Every project is different, so your estimate comes with its own written schedule, and we aim to beat the usual industry timeline on every job.
| Level of work | Typical cost |
|---|---|
| Standard finishRoof removed, new floor, walls, roof and stair, with simple finishes. The lower published Toronto range. | $300– |
| Mid-range, full fit-outStructural reinforcement, new floor, stair, roof and a full interior with bedrooms and bathrooms. | $380– |
| Typical Toronto addition totalThe total budget published for a Toronto home addition project, before contingency. | $200,000– |
| Item | Typical price |
|---|---|
| Plans and structural engineering | $5,000– |
| Site survey | $500– |
| Rent and storage while the roof is off | $6,000– |
Worked examples
- Example 1
800 sq ft second storey over a Toronto bungalow, mid-range finish
$305,000–$450,000 - Example 2
The same 800 sq ft at the lower published Toronto rate, standard finish
$240,000–$360,000 - Example 3
1,200 sq ft full second storey over a larger GTA bungalow, mid-range
$455,000–$670,000
What moves the number
- 01Size and finish level
Published Toronto rates run $300 to $450 per sq ft for a standard finish and $380 to $560 for mid-range work. High-end work starts near $650.
- 02What the house can carry
Footing, wall and beam upgrades differ on every house. Plans and structural engineering for a second storey are published at $5,000 to $12,000.
- 03Bathrooms upstairs
Each bathroom adds drains, venting, waterproofing, tile and fixtures, so it costs far more than the same floor area of bedroom.
- 04Moving out
With the roof off, most families move out. One published guide allows $6,000 to $15,000 for rent and storage over three to six months.
- 05Zoning and site access
A minor variance adds time and fees before the permit. Tight lots, street parking limits and protected trees add labour on site.
Rebates, subsidies and tax credits
- Loan up to $125,000Toronto Home Energy Loan Program
A low-interest City loan for energy work such as heat pumps, insulation, windows and doors, capped at 10% of the property’s assessed value. Toronto addresses only. Your mortgage lender must consent, and it is repaid on the property tax bill.
Program rules - Rebates by upgradeHome Renovation Savings (Ontario)
Rebates may apply to energy upgrades in the project: up to $7,700 for insulation and $100 per window or door opening, with a home energy assessment first, two or more upgrades and the follow-up done by December 31, 2026 under current terms; and, without an assessment, up to $2,000 for a cold-climate heat pump in a home heated with Enbridge gas, or up to $7,500 with electric, oil, propane or wood heat.
Program rules - Up to $7,500Multigenerational Home Renovation Tax Credit
A refundable federal credit of 15% of up to $50,000 in costs. The work must create a self-contained unit so a senior, or an adult eligible for the disability tax credit, can live with a relative. Your own labour does not count. Keep invoices.
Program rules
Ranges cover structure, roof, stair and interior fit-out, before HST. Rent while you are out, landscaping and a 10% to 20% contingency are extra. High-end custom work starts near $650 per sq ft. Prices checked in 2026. Not a quote: your estimate is built from your own measurements and choices.
Where these numbers come from
- Building Permit Fees, City of Toronto (2026 fees)
- Building Permit Review Streams, City of Toronto (2026)
- Development Charges Overview, City of Toronto (2026)
- Building By-law Schedule “B”: 2026 Classes of Permits and Fees, City of Mississauga (2026)
- 2026 Fees and Charges By-law 051-2026, Schedule “F”: Building Standards, City of Vaughan (effective February 24, 2026)
- Home Energy Loan Program, City of Toronto (2026)
- Home Renovation Savings Program, Save on Energy and Enbridge Gas (2026)
- Multigenerational Home Renovation Tax Credit, Canada Revenue Agency (2024)
- Published 2026 price guides and GTA contractor price pages (2026)
G-003 How we work
How we deliver your second-storey addition
- 1
Free Estimate
Tell us what you have in mind. We review your space and goals and give you a clear estimate at no cost.
- 2
Design + Permits
Our in-house designers model your project in 3D so you can see it and settle every choice. Our in-house engineering team prepares drawings, engineering letters and permit applications.
- 3
Material Procurement
We order cabinets, tile, stone, pavers and decking from trusted suppliers such as Unilock, Techo-Bloc, TimberTech and Trex, and schedule deliveries around the work.
- 4
Construction Process
Our crews build to code with site supervision and regular updates, so you always know where things stand.
- 5
Project Completion
Final inspection, walkthrough and clean-up. On time, within budget and beyond expectations. That is the MKC Guarantee.
Plan your project
with a free estimate.
We review your space and goals and give you a clear estimate at no cost.
A-502.4 Questions
Questions about second-storey addition
Don’t see your question? Call (647) 637-6052 or ask in your estimate request.
How much does a second-storey addition cost in Toronto?
Typical cost in Toronto and the GTA: $300 to $560 per sq ft (Finished second storey on an existing house, standard to mid-range finish). By level of work: Standard finish: $300 to $450 per sq ft; Mid-range, full fit-out: $380 to $560 per sq ft; Typical Toronto addition total: $200,000 to $500,000. The price depends most on the size of the new floor, the finish level, how many bathrooms go upstairs and how much reinforcement the existing house needs. These are typical ranges, before HST, with prices checked in 2026; your estimate is built from your own measurements and choices.
Can my house carry a second storey?
Most can, but few can without some reinforcement. The footings, foundation walls and bearing walls were sized for the house as built, and a new floor and roof add load to all of them. Our engineers check what is there, often through small openings in finishes, and design any new beams, posts or footing upgrades. The result goes into the permit drawings and your estimate.
Do we have to move out during the work?
In most cases, yes. The roof is removed, the house is open to weather for a time, and power, heat and water are interrupted while services are extended upstairs. Published guides put construction at three to six months and allow $6,000 to $15,000 for rent and storage. That cost is not part of a contractor’s price, so plan for it separately.
Will we need a minor variance?
Only if the design goes past what the zoning by-law allows on your lot, such as height, setbacks from the lot lines or total floor area. If it does, the Committee of Adjustment has to approve the variance before the City issues a building permit, and that adds time. We review the zoning before design starts, so you know early whether the plan fits as of right.
What does the building permit cost?
In Toronto, new floor area in a house is charged at $18.56 per square metre in 2026, with a minimum fee of $214.79. An 800 sq ft second storey works out to about $1,380. Mississauga charges $13.96 per square metre for a residential addition and Vaughan $21.82. No development charges apply in Toronto when the addition does not create a new unit.
Is it cheaper to build up or build out?
Published Toronto prices are close: $300 to $500 per sq ft for a ground-floor addition and $380 to $560 for a second storey. Building out needs a new foundation and uses yard, and lot coverage rules may limit it. Building up keeps the yard but needs structural work, a new stair and usually a move. The lot and the existing structure usually decide it.
What about asbestos in an older house?
Removing a roof, ceilings and walls disturbs materials that can contain asbestos in older homes. Under Ontario Regulation 278/05, suspect materials are sampled and tested by an accredited lab before work starts, and removal is classed as a Type 1, 2 or 3 operation. Type 3 removal is done by certified asbestos abatement workers and supervisors.
Can I see my second storey in 3D before work starts?
Yes. We model the new floor in 3D with its rooms, the new stair and the exterior, so you can see how the house will look and approve the design before the permit drawings are made.
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