ADU rules in Evanston

Detached ADUs, including the coach houses that are part of Evanston's historic fabric, are an allowable accessory structure citywide: Table 4-A in 6-4-6-3 lists 'Detached Accessory dwelling units (including Coach Houses) to residential building' as permitted in side and rear yards in both residential and nonresidential districts, and 6-4-6-1 permits accessory structures in any zoning district in connection with a lawfully existing principal use. One ADU is allowed per zoning lot and there is no minimum lot size. A detached ADU may be new construction or a conversion of an existing structure such as a garage. Heights are 20 feet for flat or mansard roofs and 28 feet otherwise, in both cases capped at two stories.

The zoning definition of an ADU expressly covers units that 'may be internal, attached or detached', and 6-4-6-10(A) allows an ADU to be created through new construction, alteration of an existing structure, an addition, or conversion of an existing structure. Attached and internal ADUs (basement units, additions, interior conversions) take the underlying district's yard, height, and F.A.R. or lot coverage limits rather than the accessory-structure standards. Design standards apply: only one pedestrian entrance may face the front facade, and any exterior stairs serving as the ADU's primary entrance must be on the interior side or rear of the building.

6-4-6-10(D) sets two stacked limits. Every ADU must be smaller than the floor area of the largest primary dwelling unit on the lot. On top of that, a detached ADU, or an internal or attached ADU created through new construction or an addition, may not exceed 1,000 square feet of floor area. The one exception is an internal or attached ADU created by altering an existing structure: it may exceed 1,000 square feet, but its floor area is limited to no more than one level of the existing structure (a basement, story, or half story). On tight lots the binding constraint is usually not the square footage cap but the rear-yard and lot-coverage limits carried over from 6-4-6-3.

6-4-6-10(K) is explicit: 'There is no requirement that the property owner reside on the property.' Evanston removed owner occupancy when it created the modern ADU regime in Ordinance 86-O-20 (adopted September 29, 2020), and the section has not been amended since. Two related conditions do survive: the ADU must remain under common ownership with the residential building, and occupancy of the ADU is limited to no more than one family as defined in 6-18-3. The city's own guidebook FAQ repeats the answer plainly ('No, the owner does not need to live on the property'), and the Zoning Office's R1-R3 district regulations sheet says the same.

6-4-6-10(H) states that no parking is required for an ADU under Chapter 16, and Table 16-B's own line item reads 'Accessory Dwelling Unit (including Coach house): No parking is required.' The one string attached is that existing required parking for the primary residential structure must be maintained or replaced, so an owner converting a garage into an ADU has to keep whatever parking the principal dwelling was required to have. Evanston requires two spaces per single-family detached dwelling, but the city guidebook notes that a home that already has fewer than two existing spaces does not have to add any.

An ADU is an accessory use permitted by right; it is not listed as a special use or administrative review use in any district use table, and no public hearing or discretionary approval is involved. The review is ministerial: the Zoning Administrator issues a certificate of zoning compliance under 6-3-2, then the project goes through a building permit and a certificate of occupancy. The city guidebook describes the same sequence (Zoning Analysis, Building Permit, Certificate of Occupancy) and says 'most ADUs are considered permitted use, meaning that you do not typically need a zoning variance.' The exception is a landmark property or a property in a historic district, where a certificate of appropriateness from the Preservation Commission is required first.

Nothing bars renting an Evanston ADU. Long-term rental requires annual registration under Title 5 Chapter 8 (Ordinance 141-O-18), which the city's Rental Registration page says applies expressly to accessory dwelling units, and the unit must pass a Property Maintenance Code inspection. Renting for under 30 days requires a Short-Term Rental License under Title 5 Chapter 9, rewritten by Ordinance 2-O-26 adopted February 23, 2026: licenses are capped citywide at one per hundred registered long-term rental units, listings must go through a licensed intermediary platform, and a property manager must be within three miles of Evanston. Zoning adds two permanent limits: the ADU must stay under common ownership with the residential building, so it cannot be sold or split off, and occupancy is limited to no more than one family.