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Accessory Dwelling Units in Oshawa, Ontario: design, permit and build on a single contract. A typical 700 sq ft unit estimates at $275,000-$368,500 (about $393/sq ft), with $6,500-$11,500 including Durham Region charges in municipal approvals and a April-November construction season.

Full-service accessory dwelling unit design and construction across the GTA - we take a single-family lot from feasibility review through permit approval, build and final occupancy sign-off on one contract.
Service area
Oshawa, Ontario
Durham Region
Typical build estimate
$275,000-$368,500
about $393/sq ft in Oshawa
Municipal approvals
$6,500-$11,500 including Durham Region charges
quoted separately from the build
Build season
April-November
134 cm snow · -4.1°C winter avg
Frost depth
1.2 m
footing depth, OBC Part 9
Local market
175,383
residents · walkability 50/100
Oshawa runs a residential rental housing licensing by-law covering the wards around Ontario Tech and Durham College, so in Windfields and Northglen a new secondary suite needs a licence as well as a permit. Owners planning student tenancy get the licensing test folded into the design brief, because it sets bedroom count and parking. Oshawa permits additional dwelling units and operates a rental-housing licensing regime in the university district that a new suite must satisfy.
Older large-lot neighbourhoods near downtown, plus student-rental territory around Ontario Tech and Durham College where licensing applies. Oshawa sees 134 cm of snow and -4.1°C winter averages. Ontario's 1.2 m frost-depth requirement governs every footing we pour for accessory dwelling units, and the April-November season sets the excavation window.
Four physical forms are available on a Oshawa lot - detached garden suite or laneway house, an internal basement or upper-floor suite, a garage conversion, and a factory-built module - and the lot itself, not preference, usually decides which two are realistic. We run a feasibility overlay on the parcel first - zoning envelope, servicing capacity, rear-yard access - and only then price the two forms that survive it. Bill 23 permits up to three residential units as-of-right on most serviced Oshawa lots, which removes the rezoning application from the default path.
Everything you need to know about our services.
A typical 700 sq ft build in Oshawa estimates at $275,000-$368,500 - about $393/sq ft, set by $6,500-$11,500 including Durham Region charges in approvals, a 1.2 m frost-depth footing requirement and 134 cm of annual snow load. Final pricing follows the site visit.
Related service: Our ADU services
Oshawa permits additional dwelling units and operates a rental-housing licensing regime in the university district that a new suite must satisfy. Approval costs in Oshawa run $6,500-$11,500 including Durham Region charges, quoted separately from construction so the permit stage holds no surprises.
Related service: Our ADU services
Older large-lot neighbourhoods near downtown, plus student-rental territory around Ontario Tech and Durham College where licensing applies. At 50/100 walkability, Oshawa suites usually keep one parking space: enough to clear the zoning review without surrendering the whole yard. We work regularly in O'Neill, McLaughlin, Northglen.
Related service: ADU Building Permit
It is decided by the parcel: a registered lane points to a laneway house, a deep rear yard with side access points to a garden suite, adequate head height points to a basement suite, and an existing attached garage points to a conversion. We measure all four against your Oshawa lot in the feasibility review before any design fee is charged.
Related service: Laneway Homes
Get a free, no-obligation quote from GTA ADU Builders - zoning review, permit drawings and construction for ADUs across the GTA.