Basement & Accessory Apartments in Oshawa, Ontario
Oshawa already has 3,097 registered two-unit homes and 30,000 students needing rentals. The accessory-apartment rules, real permit costs, and why there's no grant here (unlike Ajax or Whitby).
Oshawa permits up to three units on lots in nine named residential zones — a home plus up to two accessory apartments, one of which may be detached. There is no municipal grant here, unlike neighbouring Ajax and Whitby, but the rental demand is real: the city already has over 3,000 registered two-unit homes and about 30,000 post-secondary students.
HouseLyft helps homeowners in Oshawa, Ontario work out what their lot legally permits, what a suite will cost to build, what it should earn, and which programmes actually apply — then connects them with a vetted builder.
In some towns a secondary suite is a bet on future demand. In Oshawa it’s a bet that’s already paying off for thousands of owners.
The City’s own public registry lists 3,097 legally registered two-unit homes as of July 15, 2026 — up from 22 in 2008, with 335 added in 2024 alone. Behind that is a standing tenant base most GTA suburbs don’t have: roughly 30,000 post-secondary students across Ontario Tech University, Durham College, Trent University Durham and the Queen’s–Lakeridge medical program, concentrated in north Oshawa around the Windfields campus. An accessory apartment near there rents to a market that renews every September.
So the honest lead for Oshawa isn’t “could this work” — it’s “here’s who it works for, and exactly what the rules are.”
What Oshawa permits on a residential lot
Under Zoning By-law 60-94 (Section 5.12), Oshawa permits up to three dwelling units on a lot — the home plus up to two accessory apartments — with at most one of those in a detached accessory building.
This is not blanket city-wide permission. It applies in nine named zones (R1, R2, R3, R5, OSR-A, OS-ORM and the agricultural AG zones), and it is excluded on hazard lands identified by the Central Lake Ontario Conservation Authority and on lots where the main home is allowed only under an ’h’ holding symbol. Which zone your lot carries is the first thing to confirm.
3Units permitted
1 of the 3Detached accessory suite
NoneMunicipal grant
What a detached accessory unit can be
A detached accessory apartment in Oshawa is capped at 60 m² of ground-floor area (90 m² in the R1-G and R1-H zones). Its footprint is limited by the most restrictive of three tests — 8% of the lot, 50% of the house’s coverage, or that 60 m². Height is 4.5 m, and it must sit at least 3 m from the main house, 0.6 m from side and rear lot lines, with additional clearances from any railway, Highway 401/407 or pipeline corridor. A new detached unit requires a survey sealed by an Ontario Land Surveyor or engineer; an accessory building that existed before May 29, 2023 can be converted if it stays within 60 m².
Parking — and no tandem
Oshawa requires one additional space per accessory unit, and it can’t be stacked. A two-unit property needs three spaces total, a three-unit property four — each 2.75 m × 5.75 m, with the required spaces having their own street access rather than sitting one behind another. At least half of the front and exterior side yards must stay landscaped, which limits how much you can pave to solve the parking. A new or widened driveway needs a City or Regional curb-cut approval.
What the City charges
Oshawa has no ADU-specific permit fee — the amount is a rate times floor area, set by the chief building official at application, with a $160 minimum. The rates that typically apply:
Finishing a basement
Read why →Finishing a basement
$7.79/m² (with the calculated area treated as at least 50 m²)
← BackA detached building for human habitation
Read why →A detached building for human habitation
$15.56/m²
← BackHelpfully, no extra permit fee is charged for plumbing, sprinklers or mechanical systems installed as part of the same job. A separate $500 registration fee applies only where a second unit was created before July 1994; a newer unit is created and registered through the building permit itself.
On grants: none here — and that’s the honest answer
Two neighbouring Durham towns run homeowner incentives — Ajax (a $2,000–$12,000 cash grant) and Whitby (a fee-reimbursement program). Oshawa runs neither. If you’ve seen one of those advertised, check the town it actually belongs to before you count on it. What Oshawa homeowners do get is the provincial development-charge exemption, and it’s not trivial here: the City’s development charge on a home is $40,720, and a second and third unit are exempt from it by law. (Downtown Oshawa has also had $0 City development charges on all new housing since 2004, if your lot is in the growth centre.)
What an Oshawa suite earns
As of CMHC’s October 2025 Rental Market Survey, average rents in Oshawa were $1,598 for a one-bedroom and $1,780 for a two-bedroom — both high-reliability figures for the purpose-built rental market.
As always, that survey excludes the secondary market — basement and accessory apartments — where rents run higher, especially furnished student rentals near the north campus. Use the CMHC figures as a conservative floor, not a ceiling.
What we do — and what we don’t
HouseLyft establishes whether a project stands up before anyone spends money on drawings: which zone your lot carries and whether it qualifies, what the build realistically costs, what it should rent for, and which programmes genuinely apply — including telling you when a “Durham grant” belongs to a different town. Where it works, we hand you to a vetted builder and stay involved. Where it doesn’t, we say so.
We are not a lender and we do not sell mortgages.
One correction worth carrying, because it is still advertised widely: the federal $80,000 Secondary Suite Loan was cancelled in Budget 2025 and never launched. Our financing guide sets out what is actually live.
Serving Oshawa and the surrounding region
We work across Oshawa and the wider GTA, including Whitby, Pickering, Toronto and Markham — where the unit rules, zones and municipal programmes differ materially from Oshawa’s. The full list is on our service areas page.
We also handle multiplex conversions and planning and permits across Durham Region.
Common questions about Oshawa accessory apartments
Up to three — the home plus two accessory apartments — with no more than one in a detached building, in the named residential and agricultural zones. Hazard lands and holding-symbol lots are excluded.
No. Oshawa has no homeowner grant. Ajax and Whitby run programs, but those don’t apply here. The one automatic benefit is the development-charge exemption, worth up to the City’s $40,720 charge per unit.
Up to 60 m² of ground-floor area in most zones (90 m² in R1-G and R1-H), at 4.5 m height, at least 3 m from the house. A new one requires a land surveyor’s plan.
One per accessory unit — three spaces total for a two-unit property, four for a three-unit — and they can’t be tandem; the required spaces need their own street access.
There’s no flat ADU fee. Finishing a basement is $7.79/m² and a detached habitable building is $15.56/m², with a $160 minimum, plus a $500 registration fee only for units created before July 1994.
How this page was checked
Verified 20 July 2026, claim by claim — every figure above traced to the instrument it comes from.
Municipal rules and fees change — confirm your property’s zone and current terms with the City of Oshawa before committing to a project.
Find out what your Oshawa lot allows
Enter your address and we’ll come back with which zone your property carries, whether it qualifies, what a suite would realistically cost, and what it should earn — including the north-campus rental picture.
- What your lot allows
- What it should earn
- Which programmes apply
Illustrative — your report is built from your own address.