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Secondary Suites in Oshawa, Ontario: design, permit and build on a single contract. A typical 700 sq ft unit estimates at $93,500-$151,500 (about $393/sq ft), with $6,500-$11,500 including Durham Region charges in municipal approvals and a April-November construction season.

Secondary suites carved out of an existing house - main-floor, upper-level or above-garage units built to the Ontario Building Code second-unit standard.
Service area
Oshawa, Ontario
Durham Region
Typical build estimate
$93,500-$151,500
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 secondary suites, and the April-November season sets the excavation window.
"Secondary suite" is the Ontario planning term for a second self-contained dwelling inside the existing house, so the review in Oshawa turns on the interior - separate kitchen and bath, an exit that does not pass through the primary unit, and rated separation between the two. Because the shell already exists, the schedule is driven by inspection sequencing rather than by weather: rough-in, framing and insulation inspections gate one another regardless of the April-November season. Bill 23 makes up to three units as-of-right on most serviced Oshawa lots, so a secondary suite generally proceeds by building permit alone without a rezoning application.
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A typical 700 sq ft build in Oshawa estimates at $93,500-$151,500 - 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
Usually not. On a serviced Oshawa lot, Bill 23 permits up to three residential units as-of-right, so the path is a building permit rather than a six-to-twelve-month rezoning. Oshawa permits additional dwelling units and operates a rental-housing licensing regime in the university district that a new suite must satisfy.
Related service: ADU Building Permit
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