What Is a Garden Suite? Meaning, Rules and Other Names in Ontario
Short answer: a garden suite is a detached, self-contained home in the backyard of a house, on the same lot. Ontario counts it as an additional residential unit.
By Modular X Team5 min readUpdated October 2026
What is a garden suite? The plain-English meaning
A garden suite is a small, detached home built in the backyard of an existing house. It has its own entrance, kitchen and bathroom, shares the lot with the main house, and stays on the same title. Ontario's Planning Act and O. Reg. 299/19 call it an additional residential unit.
Granny flat, garden house, backyard suite: other names for a garden suite
People search for the same building under many names: granny flat, granny suite, in-law suite, garden house, backyard suite or detached ADU. Hamilton calls it a detached additional dwelling unit; Markham separates garden homes from coach houses. See also granny flats and granny pods in Ontario and what an ADU is.
Garden suite vs laneway suite
In Toronto, the lane decides. A lot that abuts a public lane for at least 3.5 m is in laneway-suite rules; otherwise it is in garden-suite rules, and a lot gets one or the other, not both. Full comparison: garden suite vs laneway suite.
What Ontario allows, and what your city decides
The Planning Act lets most serviced urban residential lots have up to three units, one of them in a detached building. Your city then sets the size, height, setbacks, fire-access path and parking. Those numbers differ: compare them in GTA garden suite rules, city by city and garden suite setback and size rules.
A garden suite is a detached, self-contained home in the rear yard of a house, on the same lot, with its own entrance, kitchen and bathroom. In Ontario it is a type of additional residential unit. It cannot be sold separately from the main house.
Both are detached homes behind a house. In Toronto, a lot whose rear or side lot line abuts a public lane for at least 3.5 m falls under laneway-suite rules; a lot without that lane frontage falls under garden-suite rules. One detached suite type per lot: a laneway suite or a garden suite, not both.
Mostly the same building with different names. Granny flat, backyard suite, garden house and in-law suite are everyday names. A coach house usually sits above or beside a detached garage, and some cities, such as Markham, define it separately in their by-laws. Your city's by-law term decides which rules apply.
On most serviced urban residential lots, yes. The Planning Act (s. 16(3) and s. 35.1) stops official plans and zoning by-laws from prohibiting up to three residential units on a parcel of urban residential land, one of which can be in an ancillary building. Each city still sets size, height, setbacks, fire access and parking.
Yes. Every garden suite needs a building permit from the municipality. Toronto reviews complete House Stream applications within 10 business days, and Mississauga targets about 15 business days for the first review of a complete application.
Yes, if the lot allows it. A modular unit is built in a factory and set by crane, so crane access on the day matters; a tight lot may point to site-built construction. The permit rules are the same either way.
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.