Six GTA municipalities, six different rule sets, and no two use the same vocabulary. This table compares what each one publishes for a detached additional residential unit — the building most people call a garden suite. Every figure links to the municipal source. Where a municipality does not publish a value, we say so rather than guessing.
Key takeaways
| Question | Short answer | Source |
|---|---|---|
| Scope | The comparison covers six GTA municipalities; terminology and local rules differ. | Municipal comparison |
| Building permit | A pre-approved design still requires a building permit and site-specific zoning review. | Pre-approved-plan FAQ |
| Unit count | Serviced urban residential lots can have three units: three in the house, or two plus one ancillary unit. | Provincial rules |
| Servicing | Burlington does not permit ARUs on private water or sewer services. | Municipal servicing rules |
| Local limits | Height, setbacks, floor area and fees still depend on the municipality. | Provincial and local rules |
Municipal sources last verified 29 August 2026. Zoning by-laws and fee schedules change — confirm with the municipality before designing to any figure on this page.
City pages: Mississauga · Toronto garden · Toronto laneway · Etobicoke · Brampton · Oakville · Milton · Burlington
The comparison table
Scroll the table sideways on a phone. Rows read across the six municipalities; the phrase "Not clearly published" means exactly that — the municipality does not publish the value, and we have not substituted one from a neighbour.
| Requirement | Toronto | Mississauga | Brampton | Oakville | Milton | Burlington |
|---|---|---|---|---|---|---|
| Municipal term | Garden suite / laneway suite | ARU (detached = garden suite) | ARU (detached = garden suite) | Additional residential unit (detached) | ARU (ADU in permit documents) | ARU (additional residential unit – detached) |
| Detached permitted | Yes | Yes | Yes | Yes | Yes, except detached not allowed in the Niagara Escarpment Plan area | Yes |
| Max ARUs per lot | One garden suite or one laneway suite | 2 (max 1 detached) | 2 (max 1 detached) | 2 (max 1 detached) | 3 with full municipal services, 2 without; only 1 may be detached | 3; only 1 may be in an accessory building |
| Servicing tier affects unit count | Not clearly published | Not clearly published | Not clearly published | Unit cap does not vary, but municipal water and sewer are required south of Highway 407 | Yes — 3 ARUs requires municipal water and sewer | Not permitted on private well, cistern or septic |
| Rear setback | Garden 1.5 m; laneway 0.0 m where the rear lot line does not abut a street or lane and has no openings, otherwise 1.0 m | 1.8 m | 2.5 m | 0.6 m in a rear or flankage yard where separation from the dwelling is at least 2.0 m, otherwise the same yard as the dwelling | Not clearly published | 1.2 m, increasing to 3 m for the portion above 4.6 m (peaked) or 3.5 m (flat) |
| Side setback | Garden 1.5 m; laneway 0.0 m with no openings, 1.5 m above 4.0 m height beside residential zones, otherwise 1.0 m | 0.6 m one storey, 1.8 m two storey (interior); 2.5 m one storey, 4.5 m two storey (street-facing) | 1.8 m interior | As rear | Not clearly published | 1.2 m, increasing to 3 m above the same height thresholds |
| Separation from main dwelling | Garden and laneway are now the same: 4.0 m if the suite is 4.0 m or less in height, 7.5 m if taller. Exception: in the East Toronto area bounded by Coxwell Avenue/Coxwell Boulevard/Massey Creek, the Don River/Sunrise Avenue, Victoria Park Avenue/Nursewood Park and Lake Ontario, a garden suite taller than 4.0 m needs only 5.0 m. | Not clearly published — Table 4.1.1.14 of By-law 0225-2007 sets lot-line setbacks but no separation from the principal dwelling, and detached ARUs are expressly excluded from the accessory-building standards by Article 4.1.2.4 | 3 m | 2.0 m, as the condition for the reduced 0.6 m yard | Not clearly published | 4 m |
| Maximum height | 4.0 m if less than 7.5 m from the main building, 6.3 m if 7.5 m or more; laneway also capped at two storeys | Sloped roof 4.6 m one storey, 6.8 m two storey; flat roof 3.0 m and 5.8 m | 4.5 m in standard residential zones; 7.5 m in Hamlet, Estate and Agricultural zones — or the height of the principal dwelling, whichever is less | 4.0 m, reduced to 2.5 m within 3.5 m of a flankage lot line | Not clearly published | 7 m peaked roof, 6 m flat roof |
| Maximum floor area | Garden suite 120 m² total, 60 m² single storey | 55 m² on lots up to 550 m² (single storey only); 10% of lot area to a maximum of 100 m² on larger lots | 35 m² in standard residential zones; 80 m² in Hamlet, Estate and Agricultural zones | Not clearly published — By-law 2024-053 sets no maximum floor area for a detached ARU. The binding constraints are accessory-building lot coverage, which By-law 2014-014 s. 6.5.2(e) sets at the greater of 5% of lot area or 42 m² of building area, and a 4.0 m height cap | Not clearly published | 80 m², or 15% of lot area in the LN5 and LN6 zones (Residential Zoning By-law 09-2026, s. 5.14(f)). Maximum lot coverage on a lot with one or more ARUs is 45% — a lot-wide figure covering all buildings, which raises the 35–40% base in LN3 to LN6 but lowers the 50% base in LN1 and LN2. |
| Parking required | None; two bicycle spaces | None additional | None for one ARU; one additional space where there is more than one | One additional space | Not clearly published | Zero for the first ARU; one for the second or third |
| Fire access path | 0.9 m × 2.1 m sprinklered, 1.0 m × 2.1 m non-sprinklered (garden); 0.9 m × 2.1 m (laneway) | 1.2 m wide × 2.1 m high | 1.2 m pedestrian path — published as a path of travel, not a fire route | Not clearly published | 1.2 m wide × 2.1 m high | Not clearly published |
| Max travel distance from street | 45 m; 45–90 m permitted with at least one additional fire-safety measure accepted by the City | 45 m | Not clearly published | Not clearly published | Not clearly published | Not clearly published |
| Registration | Not clearly published | Mandatory for second units, no fee; whether a detached garden suite must register is not clearly published | Mandatory under By-law 157-2022. A $200 Building Division registration fee, separate from the $530 Planning Division Custom Home / Garden Suites Review fee — two different fees at two different stages, not conflicting figures. The review fee itself is published as $530 on two City pages and $517 on a third | Not required; a Zoning Certificate of Occupancy is required instead | Mandatory since 1 April 2025 — $340 per ARU | Not clearly published |
| Pre-approved plans | Yes — 8 base designs in 24 fire-access variants; a building permit is still required | Yes — Studio 40 m² (430 sq ft) and One-Bedroom 55 m² (600 sq ft) | None published | None published | None published | None published |
| Development charges | $0 since 24 July 2025. By-law 845-2025 exempts the second through sixth units and one unit ancillary to the primary building, which expressly includes laneway and garden suites; carried forward in By-law 269-2026. The separate 20-year deferral programme is a 2018 laneway measure that this exemption supersedes for a garden suite | The City states development charges "will also apply for additions and garden suites" — confirm for a specific project | Municipally exempt; Education Development Charges still payable | Exempt from Town and Regional charges; education charges may apply | Exempt | Exempt; Education Development Charges may still apply |
| Other notable requirement | Laneway suites need a lot line abutting a lane for at least 3.5 m; max length 10 m, width 8 m | Building permit fees are refunded after construction and final inspections | New Zoning By-law 14-2026 is under appeal; both it and 270-2004 apply, most restrictive prevailing | By-law 2026-088, adopted 15 June 2026, introduces minimum yards for ARUs — figures above predate it | Detached ARUs not permitted in the Niagara Escarpment Plan area | A Pre-Building Approval application is required before the building permit; review takes 4–6 weeks |
City-by-city detail sits on the market pages — the Toronto rules are unpacked on our Toronto garden suite page, the lane-abutting variant on the laneway suite page, and the incentive stack west of the city on the Mississauga page.
Where the rules diverge most
Floor area is the biggest practical gap. Brampton caps a garden suite at 35 m² in standard residential zones, while Toronto allows up to 120 m² — dropping to 60 m² if the suite is single storey, and in every case less than the gross floor area of the main house — and Burlington 80 m². The same design is legal in one municipality and impossible two towns over.
Separation from the house is the second. Brampton requires 3 m and Burlington 4 m, while Toronto requires 4.0 m, rising to 7.5 m once the suite is taller than 4.0 m — with a carve-out in East Toronto, where 5.0 m is enough. Mississauga sets no separation distance from the principal dwelling at all. On a shallow lot that single number decides whether anything fits.
Only Toronto and Mississauga publish pre-approved plans. Toronto has charged $0 in development charges on a garden suite as the second unit on a lot since 24 July 2025, while Mississauga's own page still tells homeowners that charges apply. Everywhere else the soft costs are quoted project by project.
What we could not verify
Milton publishes its detached ARU permissions and its $340 registration fee clearly, but its homeowner-facing ARU guide carries no dimensional standards — those sit in Section 4.10 of Comprehensive Zoning By-law 016-2014, which a homeowner has to open the full consolidated by-law to reach. Brampton publishes the same Custom Home / Garden Suites Review fee as $530 on two City pages and $517 on a third, all citing User Fee By-law 380-2003. Brampton's new Zoning By-law 14-2026 is under appeal at the Ontario Land Tribunal, and Oakville's By-law 2026-088 has no published consolidation or in-force confirmation; both touch ARU standards directly. Treat every figure here as a starting point and confirm with the municipality before designing to it. We update this page when municipal sources change.
If you would rather skip the by-law reading, the fastest way to find out which of these numbers actually bind is to run your address through the lot check.
2025–26 rule changes (O.Reg 462/24)
Ontario Regulation 462/24 amended O. Reg. 299/19 (Additional Residential Units) under the Planning Act. It was filed and came into force on 20 November 2024, and GTA municipalities have spent 2025 and 2026 bringing their zoning by-laws into line. It applies to additional residential units — garden suites, laneway suites, basement and other secondary units — on parcels of urban residential land. What it sets province-wide:
- Angular planes: a building containing an additional residential unit may penetrate any angular plane in the zoning by-law, subject to the by-law's maximum height and minimum setbacks.
- Separation: the building must be at least 4 metres from another building on the parcel that contains a residential unit — unless the zoning by-law permits less, in which case the by-law prevails.
- Lot coverage: up to 45% of the parcel may be covered by buildings and structures; a by-law that permits more prevails.
- Floor space index: no FSI limit, subject to the by-law's maximum height and minimum setbacks.
- Minimum lot area: no larger than the by-law would require for the same parcel without additional residential units.
What it does not set: floor area caps, heights, setbacks from lot lines, fire access or fees. Those still come from each municipality, which is why the table above still differs city to city. In Toronto, for example, the City applies the 4 m separation alongside its height-based rule: a suite taller than 4 metres needs 7.5 metres of separation.
Official sources: O. Reg. 462/24 (e-Laws) · O. Reg. 299/19 Additional Residential Units, consolidated (e-Laws) · City of Toronto — Expanding Housing Options (O. Reg. 462/24) · City of Mississauga — Additional residential units.
FAQs
Keep reading
Every figure below is drawn from an official municipal source. Where a municipality does not publish a value, this page says so rather than estimating.
Municipal sources
Sources
- Ontario ERO 019-8366
- City of Toronto — Garden Suites
- City of Toronto By-law 849-2025 (garden suites, enacted 24 July 2025)
- City of Toronto By-law 847-2025 (laneway suites, enacted 24 July 2025)
- City of Toronto — Zoning By-law 569-2013 Chapter 150.8, Laneway Suites
- City of Toronto — Garden Suite Fire Access and Travel Distance
- City of Toronto — Laneway Suite Fire Access and Travel Distance
- City of Toronto — Pre-Approved Garden and Laneway Suite Plans
- City of Toronto — Development Charges Deferral Program
- City of Toronto By-law 845-2025 (development charges, enacted 24 July 2025)
- City of Toronto By-law 269-2026 (development charges, passed 26 March 2026)
- City of Mississauga — Additional Residential Units
- City of Mississauga — Zoning By-law Part 4
- City of Mississauga — Pre-Approved Garden Suite Plans
- City of Brampton — Garden Suites
- City of Brampton — Zoning By-law 270-2004 Section 10
- City of Brampton — ARU Registration By-law 157-2022
- City of Brampton — New Zoning By-law status
- Town of Oakville — Zoning By-law 2014-014 Part 4
- Town of Oakville — Zoning By-law 2014-014 Part 6
- Town of Oakville — Accessory Apartment
- Town of Milton — Understanding ARUs
- Town of Milton — ARU Registration Program
- Town of Milton zoning by-laws and maps
- Town of Milton development charges
- City of Burlington — Additional Residential Units
- City of Burlington — Zoning By-law 009-2026 Part 5
- City of Burlington — Steps to Build an ARU
Municipal rules, fees, and programs change. Confirm current requirements with the city at application. Modular X provides exact pricing only after a site-specific feasibility review.
Disclaimer: Figures cited are market estimates provided for information only and are not a quote. Municipal rules, fees, and programs change — always verify current requirements with your local authority. Modular X provides exact pricing only after a site-specific feasibility review.