Basement Renovations in Oshawa
From the older streets of Central Oshawa, McLaughlin and Lakeview to Samac, Northglen and the new homes of Windfields, we finish Oshawa basements and build legal second and third units.
Three Units, Four Parking Spaces
Oshawa permits three residential units on a lot across the whole city, with at most one of them in an accessory building. The trade-off is parking: each accessory unit needs one additional space, so a house with two extra units needs four spaces in total, each 2.75 m by 5.75 m. A hard-surfaced, unobstructed path at least 0.81 m wide must also run to the street. We check the driveway and side yard before designing anything.
Existing units have their own route. Oshawa requires every two-unit house to be registered; a unit that existed before July 1994 registers for a $500 fee, while one created after that needs a building permit to be legalized. Older housing makes this common. In the 2021 census, 6.3% of Oshawa households said their home needed major repairs, roughly double the rate in Whitby. We open up older basements carefully and price any wiring, drain or moisture work separately from the finish.
Renting is common here too: 35.8% of Oshawa households rented in 2021. Around Durham College and Ontario Tech University, including the Simcoe Street corridor, rental properties need a City licence, and since January 1, 2026 every storey of a home must have a carbon monoxide alarm. If your house is in the licensing area, we build the unit with the licence inspection in mind.
- Licensed & insured contractors
- Transparent, itemized pricing
- Permits & approvals handled for you
- On-time delivery, every project
Oshawa Basement Renovations
The basement projects Oshawa owners call us about most.
Second and Third Units
Legal basement units with separate entrances, fire separation and the parking and path the zoning requires.
Legalizing Existing Units
Taking a basement apartment created after 1994 through a building permit so it can be recognized.
Licensed Rentals
Units near Durham College and Ontario Tech built to pass the rental licence inspections.
Older Basement Overhauls
Removing dated finishes in pre-1981 homes and rebuilding with new insulation, wiring and drains.
New-Home Basements
First finishes in Windfields and Kedron homes, from rec rooms to in-law suites.
Walk-Up Entrances
Exterior stairs to a basement unit, a flat-fee item on the 2026 permit schedule.
Oshawa Basement Facts
Figures from the City and the 2021 census.
| Units allowed | 3 per lot citywide (1 at most in an accessory building) |
| Parking with two extra units | 4 spaces, each 2.75 m x 5.75 m |
| Basement finishing permit (2026) | $7.79 per m, charged on at least 50 m |
| Minimum permit fee (2026) | $160 |
| Rental licence (licensing area) | $50 application + $275 + $75 per bedroom |
| Renter households | 35.8% (2021 census) |
Oshawa Rules That Shape the Job
These local rules and conditions decide what an Oshawa basement can become.
Parking for Each Unit
One extra space per accessory unit, and four spaces of 2.75 m by 5.75 m for a three-unit lot.
Path to the Street
A hard-surfaced, unobstructed walkway at least 0.81 m wide, kept clear to the street line.
The July 1994 Line
Two-unit houses from before July 1994 register for $500. Later units need a building permit to be legalized.
Rental Licensing Area
Near Durham College and Ontario Tech, rentals need a licence: a $50 application, then $275 plus $75 per bedroom.
Repairs Behind the Walls
6.3% of households reported their home needed major repairs in 2021, so we budget for what sits behind old finishes.
Flooding in Older Areas
The City notes urban flooding mostly affects older parts of Oshawa. Floor drain backups are reported to Durham Region.
Oshawa Basement Costs
Oshawa basement finishing with us starts at $55 per square foot, and a legal second or third unit at $80 per square foot. Most family finishes we price land between $50,000 and $90,000. A legal unit generally runs $80,000 to $175,000 once it includes a kitchen, separation between units, interconnected alarms, code-compliant exits, drawings and inspections.
Older Oshawa basements often need work before the new finish goes in, such as replacing tired wiring or drains, and that preparation is shown separately in our quote. The City's own fees are modest: $7.79 per square metre to finish a basement in 2026, a $160 flat fee for a walk-up stair, and $27 per plumbing fixture. You get a fixed, itemized price after we have seen the basement.
Our Simple 5-Step Process
From first call to final inspection, this is how an Oshawa basement project works.
Reach Out
Call us or fill out our quick form to tell us about your basement.
Free Consultation
We visit your home, measure the space and talk through layout, finishes, budget and timeline.
Detailed Estimate
You receive a transparent, itemized estimate within 2 to 3 business days.
Review & Refine
We walk through the proposal together until you are fully confident.
Sign & Start
We lock in your start date and handle scheduling, permits and coordination.
Oshawa Neighbourhoods We Serve
We finish basements in neighbourhoods across Oshawa, from the lake to the north end.
Oshawa Basement Renovation FAQs
What does a legal basement unit cost in Oshawa?
How many units can I have on my Oshawa property?
Do I need a permit to finish a basement in Oshawa?
My basement apartment already exists. Can it be made legal?
Do I need a rental licence for a basement unit near Ontario Tech?
Recent Basement Renovations
Basements we have built for homeowners in Durham Region and across the GTA.
