A garden suite is a detached second home in your own backyard.

What a garden suite actually is

A garden suite is a second, self-contained dwelling built detached in the rear yard of a lot that already has a house on it. Self-contained means it has its own kitchen, its own bathroom, and its own entrance — it is a home, not a bedroom extension. Ontario legislation calls it an additional residential unit, or ARU. It stays on your title and cannot be severed and sold separately.

Garden suite or laneway suite? The lane decides

If the rear or side lot line abuts a public laneway, Toronto treats it as a laneway suite. If it does not, it is a garden suite. One lot takes one or the other, not both. The difference matters because fire access is measured differently — see laneway suites in Toronto.

What the rules cap you at, and why it varies

Every GTA municipality writes its own. Toronto permits up to 120 m² at two storeys and 60 m² at one, and the suite must always be smaller than the house it sits behind. Brampton caps a detached ARU at 35 m² in standard residential zones. Burlington requires 4 m of separation from the main dwelling and asks for no additional parking for the first backyard unit. Milton calls it an ARU and lets servicing capacity set how many units a lot can take. Mississauga and Toronto both publish free pre-approved plans; Oakville and Brampton do not.

Toronto's separation rule changed on 24 July 2025: garden and laneway suites are both now 4.0 m where the suite is no taller than 4.0 m, and 7.5 m once it is taller. There is one carve-out — in the East Toronto area bounded by Coxwell, the Don River, Victoria Park and Lake Ontario, a garden suite taller than 4.0 m needs only 5.0 m.

Full side-by-side comparison, with a municipal source for every figure: garden suite rules across six GTA municipalities.

What actually stops a build

Zoning is rarely the thing that kills a project. Fire access, trees and servicing distance are. Toronto measures laneway fire access in two segments — hydrant to fire truck, and fire truck to the suite entrance — each capped at 45 m, extendable to 90 m with additional fire-safety measures the City accepts. Arborist requirements and tree injury zones reshape more designs than setbacks do. And the servicing run from the main house to the suite is priced by the metre and appears in no brochure.

What a garden suite costs

In 2026 the market range runs roughly $400 to $650 per square foot, which puts a typical build between $275,000 and $450,000. What moves it: servicing distance, fire-access extras, trees, crane access, and finish level. Those are ranges, not a quote — exact pricing comes after a site-specific feasibility review. Detail by city: Toronto garden suite cost and Mississauga garden suite cost.

How long it takes, and why completions lag approvals

Research from the University of Toronto's School of Cities, published January 2026, found 621 laneway and garden suites completed across Toronto between 2019 and 2025, with 986 permits still active as of that January — a pipeline larger than everything finished to date. The median time from permit issuance to completion was 385 days. The approval is not the bottleneck. The build is.

Two ways to build one

Full site-built construction, or a factory-built module set on a slab poured on site, which runs the off-site and on-site work in parallel. Factory build is not automatically cheaper — it is more predictable, and on a tight urban lot predictability is usually worth more than the sticker. Crane access has to work before a module is worth ordering. Comparison: modular vs site-built.

Pre-approved plans, and what they do not cover

Toronto and Mississauga publish free pre-approved garden suite drawings, pre-reviewed against the Ontario Building Code. Using one removes the architect. It does not remove the survey, the arborist, the servicing, the grading plan, or the building permit — Toronto states plainly that a permit is still required. See garden suite plans and designs.

Where we build

Modular X designs, permits and builds garden suites across Toronto, Mississauga, Brampton, Oakville, Milton, Burlington and Etobicoke. Each municipality has its own page with its own rules.

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