What the province allows
Since the More Homes Built Faster Act, 2022, the Planning Act permits up to three residential units on a parcel where residential use is already allowed, without rezoning:
- Three units inside the primary building, or
- Two inside the primary building plus one in an ancillary building — a garage conversion, a garden suite, a laneway house
It applies automatically in settlement areas with full municipal water and sewage services, and it overrides local zoning and official plans. Legal non-conforming uses and hazard lands are excluded.
Municipalities are also barred from imposing development charges, parkland dedication or cash-in-lieu, minimum unit sizes beyond Building Code standards, or more than one parking space per unit. Under O. Reg. 299/19 that one space may be tandem, additional units are permitted regardless of when the main house was built, and occupancy does not depend on who lives in the primary unit.
What municipalities do keep control of is the part that decides whether your specific project works: servicing, emergency access, setbacks, height, and severance rules.
City by city: the rule that decides it
Toronto
Toronto has separate frameworks for garden suites (rear yard, no lane needed) and laneway suites (requires a lane). The shape of the rules is the same in both: how far the suite sits from the main house sets how tall it may be, floor area is capped relative to the main house and the rear yard, a share of the rear yard must stay soft landscaping, and no car parking is required.
The specific numbers moved recently. On 24 July 2025 Council passed by-laws 847, 848 and 849-2025 plus an official plan amendment, aligning Toronto with provincial regulation O. Reg. 462/24. Those by-laws adjusted minimum separation distances, heights, setbacks, floor area and lot coverage, and removed the angular plane restrictions that had been forcing applicants to the Committee of Adjustment. Any figure you read from before that date may be wrong, including figures still sitting on City reference pages. Confirm the current standards with Toronto before you design.
Two Toronto requirements that are stable and that decide feasibility on narrow lots:
- Fire access. An unobstructed path from the street to the suite, up to 45 m long, at least 1.0 m wide and 2.1 m high. A garden suite has only one emergency access route, and on a narrow lot with a side yard full of air conditioners, gas meters and a fence, this is the constraint that ends projects.
- Tree protection. Trees 30 cm in diameter or larger on private property are protected by by-law, and a garden suite should not result in the removal of a healthy protected tree. A Tree Declaration Form is required. The City’s own monitoring found applicants typically ran into tree protection after the design was complete, which is the expensive order to discover it in.
For laneway suites specifically: the lot needs at least 3.5 m of frontage on a lane, the suite is capped at 10.0 m long by 8.0 m wide, no vehicle parking is required but two bicycle spaces are, and the suite does not count toward floor space index or lot coverage.
Toronto building permit fees effective 1 January 2026 are $56.33 per residential unit plus $18.56 per square metre. The City also publishes pre-approved garden and laneway suite plans, which cut design cost and review time considerably.
Mississauga
Up to two additional residential units on a detached, semi-detached or townhouse lot, and only one garden suite per lot. Fire access must be an unobstructed hard-surfaced path at least 1.2 m wide and 2.1 m high, no more than 45 m from the street edge to the front door.
The rule that separates Mississauga from Toronto: building permit fees are refunded for building or legalising additional residential units, but development charges apply to additions and garden suites. Budget for them. A new garden suite address costs $81.90 plus HST, and first review runs about 15 business days. Mississauga also offers pre-approved garden suite plans.
Ottawa
Ottawa calls them coach houses, and the decisive rule is servicing. In urban and suburban areas the coach house must be served from the principal dwelling’s existing municipal water and sewer connection — it cannot have its own. Lots on municipal services may have up to two additional dwellings; lots on a well and septic are limited to one, subject to the Septic Office confirming capacity.
No additional parking is required, none in the front yard, and tandem parking in the existing driveway is permitted. Size caps are tied to lot size and the principal dwelling’s size under Section 133 of the Zoning By-law — get the current numbers from the City directly, as Ottawa’s published homeowner guide on this dates from 2017.
Hamilton
Hamilton’s detached additional dwelling unit is capped at the lesser of 75 square metres or the floor area of the principal dwelling, with a maximum height of 6.0 m, minimum 1.2 m interior side and rear setbacks, and — the constraint to check first — a minimum 7.5 m between the unit and the rear wall of the principal dwelling. Combined lot coverage of all accessory buildings plus the detached unit is capped at 25%. No additional parking is required in several zones. These figures come from the 2022 zoning amendment; confirm against the current consolidated by-law.
What it costs to build
| Item | Typical CAD |
|---|---|
| Garden suite, construction | $400–$650 per sq ft |
| Laneway suite, construction | $300–$600+ per sq ft (laneway access adds cost) |
| 600 sq ft garden suite, construction only | $240,000–$385,000 |
| Garden suite, all in, 400–1,076 sq ft | $275,000–$550,000 |
| 600 sq ft suite, all in with contingency | $365,000–$525,000 |
Toronto’s own monitoring report puts what industry told the City in the same territory: construction costs from $260,000 to over $400,000, with stakeholders asking for financing or grants to make the numbers work.
Soft costs, before a shovel moves
| Item | Typical CAD |
|---|---|
| Custom design and architectural drawings | $8,000–$25,000 |
| Pre-approved plan route instead | $5,000–$21,000 all in |
| Structural engineering | $2,000–$8,000 |
| Site survey and grading plan | $1,000–$5,000 |
| Arborist report and tree protection | $400–$3,000 |
| Trade permits (plumbing, mechanical, electrical) | $1,500–$4,000 |
| Building permit | Toronto: $56.33 per unit plus $18.56 per m² |
Total soft costs commonly land between $25,000 and $70,000 before construction starts.
Servicing: the line item that kills projects
| Connection | Typical CAD |
|---|---|
| Water and sanitary sewer | $8,000–$20,000 |
| Electrical panel and meter | $5,000–$12,000 |
| Gas | $3,000–$8,000 |
| Telecom | $1,000–$3,000 |
| Total | $15,000–$50,000 |
On a laneway lot the water and sewer have to be run from the street, under or around everything already in the way. This is the number that turns a $300,000 project into a $350,000 project, and it is almost never in the early conversation. Find it out before you pay for drawings, not after.
Development charges: the unresolved question
We are flagging this rather than answering it, because the City’s own pages do not agree with each other and the sum at stake is large.
Toronto’s development charge deferral page, updated 14 August 2026, says charges are payable on secondary dwelling units and the program defers them for 20 years from permit issuance, secured by a restriction registered on title. Toronto’s development charges overview page describes a City by-law exemption effective 24 July 2025 covering the second through sixth unit in developments of up to six units. Builders we checked state flatly that the charge is now zero.
For scale: Toronto’s single and semi-detached development charge rate is $137,846 per unit as of 26 June 2025. This is not a rounding error on a $350,000 project.
Provincially, development charges are not collected for a second unit in an existing house. Mississauga is unambiguous that they do apply to garden suites. Toronto sits in between with two pages that read differently.
Call Toronto Revenue Services and get your answer in writing before you budget. Do not take a builder’s word, ours, or a page that has not been dated.
What actually stops these projects
From Toronto’s Garden Suites Monitoring Program report of June 2025, and from builders working in the market:
| Cause | What happens |
|---|---|
| Designing before confirming eligibility | Named as the single most critical error. Drawings get produced for a lot that cannot take the suite as drawn |
| Tree protection zones | Significantly reduce buildable area, and are typically discovered after the design is complete |
| Fire access route | One access path, 45 m maximum, 1.0 m clear. Narrow lots with side-yard clutter fail here |
| Servicing discovered late | Water, sanitary, storm and electrical routing found to be far more expensive than assumed |
| Near-miss zoning numbers | Toronto found 66% of height variances could have been avoided with just 0.3 m more allowance — then the standard changed in 2025 |
| Irregular lots | Corner, through and odd-shaped lots repeatedly need site-specific relief |
| Site access for excavation | Tight laneways need specialised equipment and slower material handling |
The pattern is consistent: about 70% of Toronto applications proceeded as of right, and the ones that did not lost months at the Committee of Adjustment. The cheapest hour you will spend on this project is the one where somebody confirms, against the current by-law, that what you want fits.
Financing in 2026
One clarification first, because it is still being advertised: the Canada Secondary Suite Loan Program is cancelled. It was announced in Budget 2024, raised to $80,000 in the 2024 fall statement, promised for early 2025, and cancelled in Budget 2025 without ever opening for applications. If you see an $80,000 federal loan on a builder’s website, that page is out of date.
What does exist:
- CMHC insured refinancing for secondary suites, the main federal instrument in 2026. Borrow up to 90% of the as-improved property value, with the as-improved value below $2,000,000, amortisation up to 30 years, covering up to four units. You or a close relative living rent-free must occupy one unit, the suite must be self-contained and by-law compliant, and leases must be at least 90 days — no short-term rentals. CMHC approval must be obtained before construction starts.
- Ontario Renovates secondary suite forgivable loans, delivered by municipal and regional service managers. Amounts and eligibility differ by municipality, so you have to ask your own service manager.
- Toronto’s Affordable Laneway Suites Program has been discontinued for lack of provincial funding. The 20-year development charge deferral remains the City’s financial instrument.
Frequently asked questions
Planning, not construction. The most common causes are designing before confirming the lot qualifies, tree protection zones that shrink the buildable area, a fire access route that will not fit on a narrow lot, and servicing costs of $15,000 to $50,000 discovered after the drawings are done. Toronto issued 480 permits out of 812 applications between 2022 and May 2025.
This is genuinely unclear as of September 2026. Toronto’s deferral programme page says charges are payable and deferred for 20 years; the City’s development charges overview describes a by-law exemption effective 24 July 2025 for the second through sixth units. With the single-detached rate at $137,846 per unit, get your answer in writing from Toronto Revenue Services before budgeting. Mississauga is clear that charges do apply there.
No. The Canada Secondary Suite Loan Program was cancelled in Budget 2025 and never opened for applications. The main federal instrument in 2026 is CMHC insured refinancing, which lets you borrow up to 90% of the as-improved property value with amortisation up to 30 years, provided approval is obtained before construction starts.
On most serviced residential lots, yes. The Planning Act permits up to three units per lot as of right — three in the primary building, or two plus one in an ancillary building such as a garden suite or laneway house — in settlement areas with full municipal water and sewage. Municipal standards for setbacks, height, servicing and emergency access still apply, and about 70% of Toronto applications proceed without a variance.
A laneway suite sits on a lot that abuts a public lane and takes its access from it; Toronto requires at least 3.5 m of lot line on the lane. A garden suite sits in a rear yard with no lane, so its emergency access runs along the side of the property from the street — which is why fire access is usually the tighter constraint on a garden suite.
Roughly $275,000 to $550,000 all in for 400 to 1,076 square feet, or about $400 to $650 per square foot of construction. A 600 square foot suite with design, permits, servicing, landscaping and contingency commonly lands between $365,000 and $525,000. Toronto’s own monitoring report cites industry construction costs of $260,000 to over $400,000.
Sources
- Government of Ontario — Environmental Registry notice 019-6163 on the More Homes Built Faster Act, 2022; building a laneway house; O. Reg. 299/19 additional residential unit standards, ontario.ca and ero.ontario.ca, checked 18 September 2026
- City of Toronto — garden suites programme page; laneway suite building permit guide; zoning by-law amendment notice for by-laws 847, 848 and 849-2025 and OPA 824 (24 July 2025); pre-approved garden and laneway suite plans; building permit fees effective 1 January 2026, toronto.ca, checked 18 September 2026
- City of Toronto — Garden Suites Monitoring Program, Final Report, 27 June 2025, toronto.ca, checked 18 September 2026
- City of Toronto — laneway and garden suite development charges deferral programme (updated 14 August 2026); development charges overview; DC rates effective 26 June 2025, toronto.ca, checked 18 September 2026
- City of Mississauga — additional residential units (last modified 21 January 2026) and pre-approved garden suite plans, mississauga.ca, checked 18 September 2026
- City of Ottawa — adding a coach house or additional dwelling unit, ottawa.ca, checked 18 September 2026
- City of Hamilton — zoning by-law amendment 22-132, additional dwelling unit detached standards, hamilton.ca, checked 18 September 2026
- CMHC — mortgage loan insurance refinance for secondary suites, cmhc-schl.gc.ca, checked 18 September 2026
- Cost ranges: Maserat, Konstruction and Land Signal (Toronto design-build and advisory firms), checked 18 September 2026
Zoning standards for garden and laneway suites changed in Ontario in November 2024 and in Toronto in July 2025, and municipal figures change again without notice. Confirm every number against your own municipality before you commit money. This is not planning or legal advice.
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