ARU rules by city in Eastern Ontario
ARU rules by city vary more than most owners expect. We pulled the official zoning, fees, grants and rent data for seven municipalities so you can compare them in one place. Pick a city on the map, or sort the table below.
Compare secondary unit rules by city
| City | Units per lot | Detached unit | Size limit | Dev. charges | Best incentive | 2 bed rent |
|---|---|---|---|---|---|---|
| Kingston | Up to 4 (low-rise residential) | Yes | Up to the main house GFA | Exempt | Up to $40,000 forgivable loan (waitlisted) | $1,764 |
| Picton | 3 (serviced) / 2 (rural) | Yes, conditions apply | Set in new zoning bylaw | Exempt | No open ARU program | $1,998 |
| Napanee | 1 secondary unit (town zoning) | Not addressed in bylaw | Lesser of 45% or 100 m² | Exempt (existing house) | No ARU program found | n/a |
| Belleville | 4 total (3 ADUs) serviced | Yes, 1 per building | 100 m² or main house, 2 bedrooms | Exempt (provincial) | $5,000 to $10,000 rebate per ADU | $1,485 |
| Brockville | 3 (serviced) | Yes, 1 garden suite | Accessory buildings max 15% of lot | Exempt | Counties forgivable loan (check status) | $1,229 |
| Cobourg | 3 (2 ARUs) | Yes, 1 per lot | 50% of main home (basement can be whole) | Exempt | Up to $20,000 County loan + Town CIP | $1,650 |
| Toronto | 4 city-wide (6 in TEY + Ward 23) + 1 suite | Garden or laneway suite (one) | 120 m² (2 storey) / 60 m² (1 storey) | Exempt or deferred | DC deferral, no cash grant | n/a |
Rent sources differ by city (CMHC, City or County surveys). Toronto CMHC publishes an all-unit average of $1,917 (2025). Open each city guide for sources.
Kingston secondary unit guide
Kingston allows up to four units per lot in low-rise residential areas, including attached, detached, garage and basement ARUs. An ARU can be as large as the main house and needs one parking space. The City offers forgivable loans of up to $40,000, now waitlisted.
Kingston ARU rules County of Prince EdwardPicton secondary unit guide
In Picton and the rest of Prince Edward County, a house on municipal water and sewer can have up to three units. Rural or privately serviced lots get one extra unit, only with a hydrogeological study. Second and third units are exempt from development charges.
Picton ARU rules Town of Greater NapaneeNapanee secondary unit guide
Greater Napanee’s zoning allows one secondary unit in a single, semi or row house, capped at the lesser of 45% of the main home or 100 m². Permits cost $11 per $1,000 of construction value. One or two added units in an existing house are exempt from development charges.
Napanee ARU rules City of BellevilleBelleville secondary unit guide
Belleville allows up to three accessory dwelling units plus the main house on fully serviced residential lots since March 2025. Each ADU can be up to 100 m² with two bedrooms. The City pays rebates of $5,000 per ADU, and $10,000 for a third, while funds last.
Belleville ARU rules City of BrockvilleBrockville secondary unit guide
Brockville allows up to three units on a serviced single, semi or row house lot: three in the house, or two in the house plus a garden suite. Garden suites can be 4.0 m tall with 1.2 m setbacks. Second and third units are exempt from development charges.
Brockville ARU rules Town of CobourgCobourg secondary unit guide
Cobourg’s 2025 zoning bylaw allows two ARUs with a single, semi or townhouse, so three units in total, with one allowed in a detached building. An ARU can be 50% of the main home, or the whole basement. Town and County programs can add up to $20,000 or more.
Cobourg ARU rules City of TorontoToronto secondary unit guide
Toronto allows multiplexes of up to four units city-wide, six in Toronto and East York and Ward 23, plus one garden or laneway suite per lot. A two-storey garden suite can be 120 m² and 6.3 m tall. Development charges on rear-yard suites can be deferred 20 years.
Toronto ARU rulesWhat are Ontario's province-wide ARU rules?
Ontario's Planning Act lets owners of a serviced urban lot with a detached, semi or row house have up to three units as of right. Cities cannot set a minimum unit size or require more than one parking space per added unit, and second and third units are exempt from development charges.
| Rule | What it means |
|---|---|
| Units per serviced urban lot | Up to 3 as of right: 3 in the house, or 2 in the house plus 1 in a detached building (source) |
| Minimum unit size | Municipalities cannot set a minimum floor area for these units (source) |
| Parking | Municipalities cannot require more than one space per additional unit (source) |
| Lot coverage and FSI (O. Reg. 462/24) | At least 45% lot coverage allowed, no FSI or angular plane limits, max 4 m separation required between buildings (source) |
| Development charges | 2nd and 3rd units in or behind an existing house are exempt (source) |
| Building Code | 2024 Ontario Building Code (O. Reg. 163/24), in force January 1, 2025 (source) |
| Rural and unserviced lots | Not covered by the as-of-right rule. Each municipality decides (source) |
Federal programs for secondary units
| Program | Details | Status |
|---|---|---|
| CMHC-insured refinance for secondary suites | Up to 90% of the finished home value, under $2 million, up to 30-year amortization, up to 4 units. Owner or close relative lives on site. No short-term rentals. | Available since January 15, 2025 |
| Canada's Housing Design Catalogue | About 50 free standardized designs, including accessory dwelling units with Ontario versions. Full drawing packages, energy files and cost guides. | Ready for use since October 15, 2025 |
| Canada Secondary Suite Loan Program | Announced in 2024 as up to $80,000 at 2%. Never opened to applications. | Not available |
Not sure what your lot allows? Try the what can I build checker, then estimate payback with the ARU rent and incentive calculator. Or read our secondary suite financing guide.
Questions about ARU rules in Ontario
How many secondary units can I build in Ontario?
On a serviced urban lot with a detached, semi or row house, Ontario’s Planning Act allows up to three units as of right: three in the house, or two in the house and one in a detached building. Some cities allow more, such as four in Kingston and Belleville.
Which Eastern Ontario city has the best ARU incentives?
As of October 2026, Kingston has the largest forgivable loans (up to $40,000) but they are waitlisted. Northumberland County offers up to $20,000 in Cobourg, and Belleville pays $5,000 to $10,000 rebates per unit with funds still available.
Do I pay development charges on a secondary unit?
Usually not. Ontario’s Development Charges Act exempts second and third units in or behind an existing house, and every city in this guide applies that exemption. A brand new house with a suite may still pay charges on the main home.
Do rural properties allow secondary units?
It depends on the municipality. The provincial three-unit rule only covers serviced urban lots. Prince Edward County and Belleville allow extra units on rural lots with septic studies, while Kingston’s ARU page excludes rural properties.
Find out what your property can hold
Send us your address and what you have in mind. We will check the zoning, flag any servicing issues and tell you which incentives you may qualify for, at no cost.