Schaumburg, IL Accessory Structures: ADU Rules (2026)

Schaumburg's zoning ordinance governs the construction and use of accessory structures in residential districts. Unlike some states with ADU mandates, Illinois does not require municipalities to allow accessory dwelling units by right. In Schaumburg, single-family residential zones generally permit one dwelling unit per lot. Adding a second independent dwelling unit, whether attached (in-law suite with separate kitchen and entrance) or detached (backyard cottage), typically requires a variation or special use permit from the Zoning Board of Appeals or Plan Commission. The Village evaluates ADU requests based on compatibility with neighborhood character, adequate parking, utility capacity, and compliance with building codes. The unit must meet all applicable building, fire, and accessibility codes. A building permit is required for any construction. Setback, height, and lot coverage requirements for accessory structures apply. Converting an existing garage or other accessory structure into a dwelling unit requires meeting habitable space standards for light, ventilation, ceiling height, egress windows, and sanitary facilities. Adding a kitchen constitutes creating a separate dwelling unit under the zoning ordinance. Property owners interested in accommodating family members should consult with the Community Development Department about what improvements are allowed without triggering a zoning change.