Durham RegionOshawa, Whitby, Ajax, Pickering
Legal basement apartments in Durham Region
A legal basement apartment in Oshawa, Whitby, Ajax or Pickering costs $75,000 to $110,000 or more to build with Desire Basements and takes about three months. All four municipalities apply the same 2024 Ontario Building Code, but three of them run a registry: Oshawa issues a two-unit house registration after the final inspection, Whitby registers the unit for $268, Pickering registers it under By-law 8040/23 after Fire and Building both sign off, and Ajax handles the suite through the building permit alone. The fees, parking rules and by-laws differ at each town hall, so they sit side by side below.
- OshawaRegisters through the permit; certificate within 60 days of the final inspection
- WhitbyRegisters with Enforcement Services, $268, By-law 8156-25
- AjaxBuilding permit only; ADU rate $9.68 per m² since January 1, 2026
- PickeringRegisters under By-law 8040/23 after Fire and Building inspections
Four town halls, one Code
What each municipality publishes about a second unit inside a house, fetched from the municipal sites in October 2026. Where a figure is missing, the municipality does not publish it on its additional-unit pages; we confirm it at the counter when we file.
| Rule | Oshawa | Whitby | Ajax | Pickering |
|---|---|---|---|---|
| Registration | Mandatory under the Two Unit House Registration By-law; failing to register is an offence. A unit built on a permit receives its certificate within 60 days of the building inspector's final inspection. | Mandatory under the Additional Dwelling Unit Registration By-law 8156-25. Register with Enforcement Services after the permits close and the ESA certificate is in. | The Town's permit pages describe no separate registry; the unit is created and inspected under the building permit. | Mandatory under By-law 8040/23, with Building Services and Fire Services. Registration completes after final construction is inspected by both and fees are paid. |
| Registration fee | None listed for a new unit built on a permit. $500 applies to legalizing a unit that existed before July 1994. | $268. $534 if the unit is discovered through a complaint. $107 to transfer the registration. | Not applicable. | A one-time fee set by By-law 8040/23, invoiced by a Building Services clerk after the application is received. |
| Permit fee | Set by Building By-law 33-2009 as amended; fees rose 3% on January 1, 2026. Calculated at application. | Set by the Town's fee schedule; the ADU incentive program can reimburse it (see below). | $9.68 per square metre for an accessory dwelling unit alteration, $329 flat for a below-grade entrance, $329 minimum for a moderate permit (Building By-law 48-2023, Schedule A, January 1, 2026). | New fee schedule for applications submitted after June 30, 2026. |
| Parking | One extra space per accessory unit: three spaces for a two-unit house, each 2.75 m by 5.75 m, two of them with direct street access, no tandem. Half the front yard stays landscaped. | Per the amended Zoning By-laws (8141-24, 8142-24, 8143-24); confirm with a planning inquiry. | Per the Zoning By-law; the Town's ADU mapping tool shows eligibility by address. | The City may require at most one space per ADU under the Planning Act. |
| Units per lot | Up to three dwelling units, at most one in an accessory building. | ADUs allowed in certain single detached and semi-detached homes. | Housing plan goal of up to four homes per lot; ADU rules per zoning. | Up to two ADUs on a detached, semi-detached or townhouse lot: two inside the house, or one inside and one detached. |
| Entrance | A hard-surfaced, unobstructed path at least 0.81 m wide from the unit entrance to the street line. | Below-grade entrance fee reimbursable under the incentive program. | Below-grade entrance permit, $329 flat. | A separate exterior entrance is one of the markers of a separate unit. |
Sources: City of Oshawa, Accessory Apartments and Two-Unit Houses (oshawa.ca); Town of Whitby, Additional Dwelling Units (whitby.ca); Town of Ajax, Building By-law 48-2023 Schedule A, January 1, 2026 (ajax.ca); City of Pickering, Additional Dwelling Units (pickering.ca). Municipal fees change; confirm before you file.
Whitby is paying people to do this, until December 31, 2026
The Town of Whitby's Additional Dwelling Unit Incentive, funded by the federal Housing Accelerator Fund, reimburses select Town fees for an ADU once the permit is issued: the ADU building permit fee, the registration inspection fee, the curb cut fee and the below-grade entrance fee where they apply. The complete permit application has to be in on or before December 31, 2026, the permit issued on or after April 1, 2024, and the unit registered with By-Law Services by March 31, 2027, or the incentive is repaid. The Town says there will be no extensions. Ajax ran a similar grant and has closed its intake.
Development charges are the other saving, and it applies across Durham: an ADU inside an existing home is exempt under Ontario Regulation 454/19. Whitby notes that education development charges can still apply where the house itself was occupied for under 12 months. Our rebates and tax credits page lists every program still running in 2026.
Three months, in order
What a Durham suite build looks like from the first visit to the registration certificate. The construction stretch carries a written completion date backed by our $200 a day on-time guarantee.
Free in-home consultation, measurements, a ceiling-height check against 1.95 m (1.85 m under beams and ducts), and a look at where the entrance and the parking will go.
Free 3D design of the suite. Permit drawings prepared and stamped by a licensed structural engineer while you finalize finishes.
Filed with the municipality: Oshawa and Whitby portals, Ajax by portal or email, Pickering through mycity. Review runs while materials are ordered.
Demolition, framing in wood studs with metal tracks, the 30-minute fire separation, interconnected smoke and carbon monoxide alarms, the egress window.
Kitchen and bathroom plumbing, electrical with the ESA inspection, HVAC. Whitby wants the ESA Certificate of Acceptance in hand before it registers.
Drywall, tile, vinyl plank over subfloor, cabinetry and stone chosen in the 3D design, doors at 810 mm for the suite and 760 mm for bedrooms.
Final building inspection, Fire Services where the municipality requires it, then the registration certificate. Oshawa's arrives within 60 days of the final inspection.
What it costs, and what it earns
Every basement is priced from the same quote sheet, line by line: a 1,000 sq ft basement with a three-piece bathroom comes to about $67,800 before HST, and the price per square foot falls as the basement grows because the permit, bin, breakers, stairs and bathroom cost the same at any size. A suite adds the Code lines you can read on the quote: kitchen rough-ins at $1,800, fire separation, alarms, the egress window or a separate entrance at $15,000 to $25,000. That is how a purpose-built Durham suite lands at $75,000 to $110,000 or more, with underpinning ($60,000 to $120,000) only where an older Oshawa or Pickering bungalow sits under the 1.95 m minimum.
GTA legal suites rent for $1,700 to $2,400 a month in 2026. At $2,000 a month, a $95,000 suite pays back its gross cost in roughly four years, before property tax, insurance, utilities and income tax. Price your size on the calculator, then read the rental income guide.
Two things Durham tenants and insurers will ask
The Region of Durham tells renters that a landlord's insurance "does not usually cover your personal belongings," and prices tenant insurance for a one or two bedroom apartment at $12 to $40 a month. Put it in the lease. Whitby warns owners that an undisclosed rental unit "may cause your insurance coverage to be null and void," and that income from an illegal unit may not count toward a mortgage. The registration certificate answers both. More on the insurance page.
Sources: Region of Durham, Tenant Insurance (durham.ca); Town of Whitby, Risks to a landlord for an illegal or unsafe ADU.
Durham questions
Do I have to register a basement apartment in Oshawa?
Yes. Oshawa's Two Unit House Registration By-law requires every two-unit house to be registered, and failing to register is an offence. A new unit built on a building permit receives its registration certificate within 60 days of the building inspector's final inspection; the $500 registration fee applies to units created before July 1994.
What does Whitby charge to register an additional dwelling unit?
$268 to register an ADU with Enforcement Services, $534 if the unit is discovered through a complaint, and $107 to transfer a registration, under By-law 8156-25. The Town's incentive program can reimburse the permit and registration inspection fees for complete applications filed by December 31, 2026.
How much is a basement apartment permit in Ajax?
Ajax prices an accessory dwelling unit alteration at $9.68 per square metre under Building By-law 48-2023, Schedule A (January 1, 2026), with a $329 minimum for a moderate permit and a $329 flat fee for a below-grade entrance. The Town's building pages describe no separate registry.
How many basement units can a Pickering house have?
Up to two additional dwelling units on a detached, semi-detached or townhouse lot: two inside the main residence, one in a detached building, or one of each. Every ADU must be registered under By-law 8040/23 after Fire Services and Building Services inspect the finished unit.
How much parking does a second unit need in Durham?
Oshawa asks for one extra space per accessory unit, so three for a two-unit house, each 2.75 m by 5.75 m with no tandem parking for two of them. Pickering can require at most one space per ADU. Whitby and Ajax set parking in their zoning by-laws, which we confirm for your address before the design is final.
How much does a legal basement apartment cost in Durham Region?
$75,000 to $110,000 or more with Desire Basements for a purpose-built suite, before HST and municipal fees. A 1,000 sq ft basement with a three-piece bathroom prices at about $67,800 on our quote sheet; the kitchen, fire separation, alarms and entrance are added as visible lines, and underpinning only where the ceiling is under 1.95 m.
Legal basement apartments by city
Basement renovations in Oshawa, Whitby, Ajax, Pickering and Clarington. See the project gallery for finished suites and the Ontario legal basement requirements post for the Code in detail.
One Code. Four counters. We know the way.
A free in-home visit anywhere in Durham, a free 3D design, an itemized quote within 24 to 48 hours. Based in Richmond Hill, serving the GTA since 2017.