“ADU allowed” does not mean every kind of project is allowed. Before checking a use rule, describe what is proposed: a unit inside the main home, an attached addition, a conversion of a garage or other accessory building, a new detached structure, a factory-built unit, or continued use of a unit that already exists.
Classify the building and its relationship to the home
Local definitions may turn on whether a unit shares a wall with the principal dwelling, sits above or within a garage, is in a detached accessory building, or occupies space inside the home. Edmonton, for example, defines a secondary suite within specified house forms and excludes apartments, supportive housing, and boarding or lodging houses under its stated classification. Toronto distinguishes a garden suite from a laneway suite based on the parcel’s relationship to a public lane. These labels describe local law; they are not interchangeable across cities.
Check the permission for that project state
Read the applicable zone table for the exact form and the primary dwelling on the lot. A rule may allow an internal conversion but place additional conditions on detached construction, or may treat a junior unit differently from a full ADU. Minneapolis distinguishes internal, attached, and detached application types; its guidance identifies an owner-occupancy covenant for internal units specifically, so it should not be extended to other forms without checking the current rule. Raleigh’s FAQ lists detached, attached, internal, above-garage, and basement forms, illustrating why the local definition and district list must be read together.
An existing unit needs a status check
Physical existence is not proof of lawful status. Ask the permitting authority for the unit’s permit and approval history and compare the approved plans with current use. Portland says unpermitted work must be permitted as if it were new work; tax information does not substitute for permit records. Eligibility to propose a new unit, eligibility to regularize an existing one, and proof that a unit is already legal are different outcomes.
Keep technical approval separate
Zoning eligibility does not establish building-code compliance, fire safety, foundation suitability, utility capacity, or approval to occupy. Factory-built or modular construction can also have a separate state certification and local installation review. Use the appropriate building, fire, utility, and permit process after the zoning form and status are clear.
For a jurisdiction-specific comparison, see San Diego’s ADU and JADU forms and Winnipeg’s attached and detached secondary-suite rules. An existing or uncertain-status unit needs its own permit-history review before relying on a zoning screen.