Eligibility and Zoning

An ADU, garden suite, laneway house, secondary suite, coach house, or annexe is not a universal legal category. Whether a second dwelling may be built depends on the property’s jurisdiction, the local term and definition, the primary dwelling, the proposed form, and the current zoning rules.

Start with the property and its authority

Use the street address or parcel identifier to locate the property in the official zoning map or property information service. Confirm which municipality and planning authority govern it, then check the current zoning by-law, land-use table, and any state, provincial, or national rule that affects local authority. A citywide summary is a screening aid; it cannot establish the result for an unexamined parcel.

Choose the question that matches your project

• Can I build an ADU on this property? follows the authority and local-definition checks.
• How do I check whether an ADU rule is in effect for my property? separates proposals, effective rules, updated text, and property coverage.
• Which zone allows an attached, detached, or converted secondary dwelling? explains how permission changes by zone and project form.
• What lot size, frontage, and unit-count rules apply? separates eligibility thresholds from later design limits.
• Is a garage, basement, addition, or detached ADU eligible? distinguishes project states and existing-unit status.
• How do overlays change eligibility? covers flood, heritage, agricultural, and other separate authority checks.

Focused location guides

United States — cities and counties

• Albuquerque casita eligibility
• Austin ADU eligibility
• Bellingham ADU eligibility and the Lake Whatcom watershed
• Boston ADU zoning eligibility
• Charlotte ADU eligibility
• Cheyenne ADU eligibility
• Chicago ADU eligibility
• Houston secondary dwellings and land-development rules
• Long Beach ADU zoning eligibility
• Mesa ADU eligibility and unit count
• Miami-Dade County ADU eligibility
• Milwaukee ADU eligibility by form
• New York City ADU eligibility
• Orlando ADU zone and lot-size eligibility
• Philadelphia ADU zoning eligibility
• Phoenix ADU count and zoning
• Sacramento ADU eligibility on multifamily and historic properties
• San Antonio ADU eligibility
• San Diego ADU and JADU eligibility
• San Francisco ADU eligibility
• San Mateo ADU unit-count eligibility
• Seattle ADU count and zoning
• Spokane ADU zoning eligibility
• Tucson ADU count eligibility

United States — state and county frameworks

• Arkansas ADU eligibility under the municipal minimum
• Connecticut as-of-right ADU zoning
• Massachusetts protected-use ADU eligibility
• Nevada statewide ADU eligibility
• New Hampshire ADU and existing-structure eligibility
• Vermont ADU zoning and flood eligibility
• Washington rural detached ADUs and county adoption

Canada

• B.C. small-scale multi-unit housing eligibility
• Calgary secondary or backyard suite
• Cambridge additional residential units
• Kitchener’s four-unit ADU screen
• Mississauga additional residential units
• Ontario ARUs in prime agricultural areas
• Toronto garden-suite zoning
• Winnipeg secondary-suite zoning

United Kingdom

• Aberdeenshire ancillary accommodation and planning
• Belfast ancillary accommodation or a separate dwelling
• Cornwall annexe planning
• Rother annexe planning permission
• Wales outbuilding and secondary-dwelling planning

Each guide identifies what its cited authority says and what remains subject to current mapping, code, overlay, project, and parcel checks. Location examples do not establish a universal rule or a parcel-specific approval.

Keep the result qualified

“Allowed in principle” is different from a parcel-specific zoning clearance, building approval, available utility service, or permission to occupy an existing unit. Verify the actual parcel, project form, current code and map, overlays, permit history, private restrictions, and other approvals with the responsible authorities before relying on an eligibility result.