Detached housing is not the same permission as an internal suite
Municipalities use different names—garden suite, laneway house, coach house, detached accessory dwelling, backyard suite or detached additional residential unit. The important distinction is physical: this is a separate building or a dwelling in a detached accessory structure, so the site-planning questions are usually broader than for a suite inside the main house.
Check the zoning form first
Confirm that the current zone permits the detached form you are considering. A municipality can allow a secondary suite inside a house while limiting or prohibiting detached units, or it can permit both but count them differently toward the maximum dwellings on the parcel.
Site geometry becomes a major branch
Detached units can depend on rear or side setbacks, building height, lot coverage, minimum separation from the principal dwelling, emergency or fire access, lane access, easements and the usable rear-yard area. A large lot is not enough if the buildable area is constrained by a watercourse, steep slope, protected tree area, covenant or other overlay.
Servicing must be checked before design hardens
Confirm how the new dwelling will receive water, sanitary service and utilities. On municipal systems, an additional unit can still trigger connection, capacity or upgrade requirements. On onsite septic, the approving authority may require evidence that the system and site can support the added residential load.
Parking and development permits can be separate controls
Some municipalities impose an additional parking requirement; others reduce or remove minimums in defined transit areas. A development permit may also be required for form/character, environmental, hazard or other mapped areas even when the zoning allows the housing form.
Use the local term and local checklist
Do not translate “laneway house” rules from one city into “garden suite” rules in another. Open the municipal page, confirm its defined term, then follow the building/development permit path for that form.