Garden suites & ADUs · Oshawa

Garden Suites in Oshawa

Oshawa calls a garden suite an accessory apartment in an accessory building. Up to 3 units are allowed on a lot, and one of them can be in an accessory building.

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The rules, in plain language

What Oshawa allows

Oshawa allows accessory apartments in accessory buildings in its R1, R2, R3, R5, OSR-A, OS-ORM, AG-A, AG-B and AG-ORM zones, under Sections 5.1 and 5.12 of Zoning By-law 60-94.

Size and coverage

Combined coverage of all accessory buildings is the most restrictive of: 8% of the lot, 50% of the house's lot coverage (100% in R1-G and R1-H), or 60 m² ground floor area (90 m² in R1-G and R1-H).
An accessory building existing as of May 29, 2023 can be converted if the apartment is no more than 60 m².
Source: City of Oshawa: Accessory Apartments, as of November 1, 2026

Height

Maximum 4.5 m, or 5 m in R1-G and R1-H, measured to the highest peak at the front elevation.
Source: City of Oshawa: Accessory Apartments, as of November 1, 2026

Setbacks and location

0.6 m from the interior side and rear lot lines. The exterior side follows the zone's side yard.
At least 3 m from the main house. Usually not in the front yard.
30 m from a railway, 14 m from Highway 401/407 property and 7 m from a pipeline corridor.
Source: City of Oshawa: Accessory Apartments, as of November 1, 2026

Access and landscaping

A hard-surfaced walkway at least 0.81 m wide from the entrance to the street line.
Minimum parking and 50% landscaped open space in certain yards.
Not on hazard lands identified by the Central Lake Ontario Conservation Authority.
Source: City of Oshawa: Accessory Apartments, as of November 1, 2026

Check with the city: Oshawa's page lists parking requirements, but we haven't reproduced them here, so confirm them for your lot. Fees, development charges and servicing aren't covered. Lots with an "h" holding symbol on the main dwelling can't have accessory apartments.

How we build it

Five ways to build in Oshawa

Geohaus factory-built

Perimeter Homes is a Geohaus partner. Studio, one- and two-bedroom layouts built in a factory and set on your lot.

See the Geohaus layouts

Modular / prefab

Factory-built modular garden suites and backyard homes, with sizes adjustable to your lot and local rules.

Browse the model gallery

Custom stick-built

Framed on site for tight, sloped or oddly shaped lots, or a layout no catalogue covers.

How custom works

The Suite

Our own two-bedroom, two-bath concept with a covered porch. Concept design.

See The Suite

The Bunkie

A compact backyard suite for a home office, guest room or studio.

See The Bunkie

Every design still has to fit Oshawa's zoning for your lot. We check that before you commit.

Finished Geohaus garden suite (partner build)

Common questions

Oshawa garden suite FAQ

How big can a garden suite be in Oshawa?

Coverage for all accessory buildings is the most restrictive of 8% of the lot, 50% of the house's coverage, or 60 m² ground floor (more in R1-G and R1-H).

How tall?

4.5 m, or 5 m in R1-G and R1-H.

How far from the house?

At least 3 m.

Sources