Garden Suite, ARU, ADU, Coach House: Same Building, Different Name Tag
Ontario has at least eight names for a small home in the backyard, and every town picked its favourite. The province’s legal term is “additional residential unit” (ARU). The one word that can trip you up is “garden suite”, because in many townships it still means a temporary, portable unit with a removal date.
At a glance
Same idea, different by-law wording. The word your town uses is the word you search for in its zoning by-law.
A garden suite, ARU, ADU, coach house, laneway suite and backyard home are all a self-contained second (or third) home on the same lot as a house. Ontario law calls them “additional residential units”. The exception: under section 39.1 of the Planning Act, a “garden suite” is a portable unit allowed by a temporary use by-law for up to 20 years. Rural townships often mean that one.
The Province Wrote One Word. The Towns Wrote Their Own.
When Ontario passed Bill 23 in November 2022, the Planning Act started requiring urban, fully serviced lots to allow up to three units. The law calls those units additional residential units, and the supporting regulation is O. Reg. 299/19, Additional Residential Units. You can read the government’s summary on the Environmental Registry notice for Bill 23.
But most cities already had their own programs by then, with their own names, and nobody wanted to reprint the brochures. So Toronto kept “garden suite” and “laneway suite”, Ottawa kept “coach house”, Kitchener went with “ADU” and “backyard home”, and Barrie and Burlington used the provincial “ARU”.
For a homeowner this is mostly a nuisance. It becomes a real problem in two places: when you search a zoning by-law for the wrong word and conclude “not allowed”, and when a township’s “garden suite” turns out to be a temporary permission you have to renew or remove. We’ve watched both happen.
Every Name, What It Usually Means
“Usually” is doing real work in that heading. Always read the definition section of your own town’s zoning by-law, because the definition there is the one an examiner applies.
| Term | What it usually means | Legal footing | Where you hear it |
|---|---|---|---|
| Additional residential unit (ARU) | Any self-contained unit added to a lot with a house: in the basement, in an addition, or in a separate building out back | Planning Act and O. Reg. 299/19 (the province’s term) | Barrie, Burlington, provincial documents, many GTA and Simcoe towns |
| Additional dwelling unit (ADU) | Same thing as an ARU; “detached ADU” means the backyard version | Municipal zoning wording | Kitchener, Guelph, Hamilton, Tiny Township |
| Garden suite (city meaning) | A permanent, self-contained unit in a separate building in the rear yard, not on a lane | Municipal zoning (for example Toronto By-law 569-2013) | Toronto, Mississauga, Brampton |
| Garden suite (Planning Act meaning) | A one-unit detached residential structure with a kitchen and bathroom, ancillary to an existing house and designed to be portable | Planning Act s.39.1, temporary use by-law up to 20 years, extensions of up to 3 years each | Rural townships, for example Selwyn, Cavan Monaghan, Essa, Tiny |
| Coach house | A detached unit in the rear yard; can be one storey or over a garage | Municipal zoning | Ottawa |
| Laneway suite | A detached unit at the back of a lot that faces a public lane | Municipal zoning, with different access rules from garden suites | Toronto |
| Backyard home / tiny house | Kitchener’s plain-English name for a detached ADU, which can hold one or two units | Municipal zoning | Kitchener |
| Secondary suite / second unit / secondary dwelling unit | Older and more general names, often meaning a basement or in-house apartment, sometimes any added unit | Older municipal by-laws; the 2024 Building Code also defines “secondary suite” for its own purposes | Collingwood (“second units”), Tiny FAQs, many older guides |
| Granny flat / granny pod | Marketing and family slang for a small unit for a parent; not a legal category anywhere in Ontario | None. The building is still judged as an ARU, a temporary garden suite, or a trailer | Ads, real estate listings, kitchen tables |
| In-law suite | Slang for a unit used by family, usually inside the main house | None on its own; it is an ARU in the eyes of the by-law | Everywhere |
Last checked October 2026 · Sources: ERO 019-6197 (Bill 23 ARUs), City of Toronto Garden Suites, City of Kitchener ADUs, Selwyn Township garden suite guideline
Which Word to Search in Your Town’s By-law
These are the words each town uses on its own official page. Open the link, then search the zoning by-law for that exact word plus “accessory” and “ancillary”.
| Municipality | Word on the official page | What we noticed |
|---|---|---|
| Toronto | Garden suite / laneway suite | Two separate rule sets. If your lot backs onto a public lane, you are in the laneway rules, not the garden suite rules. City page |
| Mississauga | Garden suite (also ARU) | Free pre-approved garden suite plans; fourplexes allowed as of right since December 2023. City release |
| Brampton | Garden suite | Has its own garden suite review and registration process. City page |
| Ottawa | Coach house | Rural lots on private well and septic face extra review for water and sewage. City page |
| Kitchener | ADU / backyard home | Up to four units per lot; a backyard home can hold one or two of them. City page |
| Guelph | Detached ADU | One or two ADUs in a detached structure. City page |
| Hamilton | Detached additional dwelling unit | Hamilton publishes configuration sheets for corner and interior lots. Sample sheet |
| Barrie | ARU | Up to four units per lot and one parking space per ARU. City page |
| Burlington | ARU | Has an ARU Look-up Tool and a Garage Conversion Kit. City page |
| Tiny Township | Additional dwelling unit; garden suite as a temporary use | The township page says garden suites are temporary, by temporary use by-law for up to 20 years. Township page |
| Cavan Monaghan, Selwyn, Essa | Garden suite (temporary) | Portable unit, owner signs an agreement covering removal. Very different from a city garden suite. |
Last checked October 2026 · Sources: municipal pages linked in each row
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“Garden Suite” in a Township Can Mean Temporary
This is the trap that costs real money. The Planning Act has had a garden suite section for decades, written for exactly one situation: a portable unit beside the farmhouse for an aging parent, allowed for a while and then hauled away. The township passes a temporary use by-law for up to 20 years, council can extend it in chunks of up to three years, and you sign an agreement about installation, maintenance and eventual removal. Some townships also want security posted.
If you build a $300,000 permanent home on a frost wall under that kind of permission, you have built a permanent home on temporary paper. Lenders notice. Buyers’ lawyers notice. The township notices when the term runs out.
Since Bill 23, many rural municipalities have also added a permanent detached ARU option, often with tighter size and distance rules and a septic review. So in a township you may have two doors to choose from. Ask the planner directly: “Is this a permanent additional residential unit, or a temporary garden suite under section 39.1?” Write the answer down. Our full guide to the temporary route is at Temporary Garden Suites in Ontario.
Rule of thumb: if the word “portable”, “temporary” or “removal” appears anywhere near the definition, you are reading the section 39.1 kind of garden suite. Price your foundation and financing accordingly.
Six Name Mix-ups We See Every Year
Searching the by-law for the wrong word
You search Ottawa’s zoning for “garden suite”, find nothing useful, and decide it’s not allowed. Ottawa calls it a coach house. Search every name on this page before you give up.
Assuming a coach house has to sit over a garage
Historically a coach house was the apartment above the carriage barn. In Ottawa’s rules it’s simply a detached secondary dwelling, and the height allowed depends on your zone and lot. The name tells you nothing about the shape.
Buying a “granny pod” that is legally a trailer
A unit on wheels with a VIN and a licence plate is usually treated as a vehicle, not a building, and most zoning by-laws don’t let anyone live year-round in a vehicle on a residential lot. “Granny pod” is a sales word. See Granny Pods in Ontario.
Treating a laneway lot like a garden suite lot
In Toronto, if your rear lot line touches a public lane you are in the laneway suite rules, with different access and size rules. Plans drawn to the wrong set go back for revisions.
Calling it a “bunkie” to dodge the permit
If it has a kitchen and a bathroom, it’s a dwelling unit no matter what you call it. The inspector looks at the plumbing, not the sign over the door. Our bunkie vs garden suite guide explains where the real lines are.
Using the town’s word on your tax forms
The CRA doesn’t care what Barrie calls it. For the multigenerational credit the test is a “self-contained secondary unit” with a private entrance, kitchen, bathroom and sleeping area. Details in our tax credit guide.
The Other Rulebooks Use Other Words Again
Zoning is only one of the rulebooks your project lives under. Each one has its own vocabulary, and each one decides something different.
Ontario Building Code
The Code cares about construction, fire safety and exits, not what you call the unit. A detached garden suite is reviewed as a house in its own right. The 2024 Code (in force January 1, 2025) added a “secondary suite” definition with relief for houses containing up to two suites.
Canada Revenue Agency
Uses “secondary unit” for the multigenerational credit and talks about “housing units” for HST. A CRA technical letter has confirmed a detached carriage house or laneway house can qualify for the credit where local rules allow a detached unit.
CMHC and lenders
CMHC’s refinance product talks about adding “secondary suites”, up to four units. Your bank’s appraiser will want to know whether the unit is legal, permanent and can’t be severed. See financing a garden suite.
Insurance and MPAC
Your insurer wants to know if it is lived in, by whom, and whether rent changes hands. MPAC assesses it as added value to the property. Neither cares about the name; both care about the use. See property tax.
Rules of thumb for reading any Ontario by-law: 1) read the definitions section first; 2) find the word for a detached unit and the word for an accessory building; 3) check whether a separate “temporary use” section exists; 4) look for a servicing clause (municipal water and sewer or private septic); 5) note every number with its unit, because 4.5 m and 4.5 ft are different buildings.
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Garden Suite Names, Answered
Is a garden suite the same as an ARU in Ontario?
In cities, yes. A Toronto or Mississauga garden suite is a detached additional residential unit under the Planning Act. In many rural townships, no. There a garden suite often means the Planning Act section 39.1 version: a portable unit allowed by a temporary use by-law for up to 20 years, with a removal agreement. Ask your planner which one you are applying for.
What is the difference between an ADU and an ARU?
Only the town that wrote the by-law. ARU (additional residential unit) is the term in provincial law. ADU (additional dwelling unit) is the wording Kitchener, Guelph, Hamilton and others chose. Both mean a self-contained unit with its own kitchen, bathroom and sleeping area added to a lot with a house.
What is a coach house in Ottawa?
Ottawa’s name for a detached secondary dwelling in the rear or side yard. It does not have to be above a garage. Size and height depend on the zoning by-law and your lot, and rural lots on private well and septic face extra review. Start at the City of Ottawa’s coach house page.
Is a laneway suite a garden suite?
In Toronto they are cousins with separate rules. A laneway suite sits on a lot that abuts a public lane. A garden suite is a rear-yard unit on a lot that does not. The access, fire route and size rules differ, so plans drawn for one will not pass under the other.
Is a granny pod legal in Ontario?
Granny pod is not a legal term. What matters is what the unit is. If it is a permanent building, it is an ARU and needs zoning compliance and a building permit. If it is portable and the township uses temporary garden suites, it may go through a temporary use by-law. If it is on wheels with a licence plate, it is usually a vehicle, and most by-laws do not allow living in one year-round.
What does secondary dwelling unit mean?
It is an older, general phrase for an added unit, often a basement apartment. Some by-laws still use it for any additional unit, including detached ones. Read the definition in your own by-law to see if it covers a separate building.
Does the name change the taxes or the tax credit?
No. The CRA applies its own tests. For the Multigenerational Home Renovation Tax Credit, the unit must be a self-contained secondary unit with a private entrance, kitchen, bathroom and sleeping area that meets local rules, whatever the town calls it.
Can I sell a garden suite separately from my house?
Generally no. Toronto says outright that a severance putting the garden suite on its own lot is not permitted, and the provincial agricultural ARU rules say the same for farm lots. Plan on the suite staying with the house.