Whitby and Brooklin still have a large stock of 1950s detached garages on deep lots - structurally sound shells sitting on shallow slabs. Converting one into a secondary suite is cheaper than a new ADU build only when the slab passes a frost-depth inspection at Ontario's 1.2 m requirement, and in Whitby roughly half of them do not.
Whitby Garden Suites & Secondary Suites
Whitby permits additional dwelling units; the Brooklin heritage area and the Downtown Whitby Heritage Conservation District add design review. The practical starting point in Whitby is the lot itself: Generous older lots in Downtown Whitby and Brooklin with detached garages that convert well, plus newer Williamsburg subdivisions. That is what decides whether the answer is a detached garden suite, a laneway house, a garage conversion or a basement unit. We serve Brooklin, Downtown Whitby, Williamsburg, Pringle Creek, Rolling Acres and the neighbouring areas. Permit, review and regional charges in Whitby typically total $7,000-$12,500 including Durham Region charges. With a population of 138,501 and employers such as Lakeridge Health Whitby, Durham College, 369 Peacekeepers Barracks in the local market, a legal second unit rents quickly - and the April-November working window means design and permitting should start well before you intend to build.
