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SB 4071

MUNI CD-ACCESSORY DWELLINGS

104th Regular Session Introduced by Javier Cervantes and 8 co-sponsors

Starting Jan 1, 2027, Illinois municipalities must allow ADUs in all single-family zones with limited extra requirements, and may not impose extra controls beyond typical single-fa

Added as Co-Sponsor Sen. Steve Stadelman
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Bill Summary · SB 4071

Summary of SB4071 (104th General Assembly, Illinois)

Main purpose

SB4071 seeks to require municipalities to allow accessory dwelling units (ADUs) in residential areas starting January 1, 2027. The bill aims to expand housing options by enabling ADUs in all zoning districts that permit single-family dwellings, with limited constraints beyond those applied to single-family homes without ADUs.

Key provisions and changes

  • Definition: An accessory dwelling unit is a residential living unit on a lot containing a single-family dwelling, providing independent living facilities (sleeping, eating, cooking, sanitation) on the same parcel as the principal dwelling. ADUs can be either detached or attached to the primary dwelling.
  • Mandatory authorization by ordinance (effective date): Beginning January 1, 2027, every municipality must adopt an ordinance authorizing the development of ADUs.
  • Zoning and development freedom:
    • ADUs must be permitted in all zoning districts that allow single-family dwellings.
    • Municipalities may not impose requirements beyond those that apply to single-family dwellings without ADUs, including:
    • Lot size
    • Setbacks
    • Aesthetic requirements
    • Design review
    • Frontage
    • Space limitations
    • Other controls (beyond those for standard single-family homes)
  • Construction options:
    • ADUs may be new structures or created from existing structures (e.g., attached/detached garages, attics, basements, backyard cottages).
  • Single-ADU limit:
    • A municipality is not required to permit more than one ADU on a single-family dwelling.
  • Construction timing:
    • ADUs may be constructed at the same time as the principal dwelling unit.
  • Restrictions municipalities may not impose:
    • No requirement for additional parking spaces beyond what is required for single-family dwellings without ADUs.
    • No requirement that occupants of the ADU have a familial relationship with occupants of the principal dwelling.
    • No minimum or maximum limits on ADU size (square footage) or the number of bedrooms.
  • Home rule impact:
    • Home rule municipalities may not regulate ADUs in a manner inconsistent with SB4071.
    • The section is stated as a limitation under the Illinois Constitution on the concurrent exercise of power by home rule units.

Who/what is affected

  • Municipalities in Illinois: Required to authorize ADUs by ordinance starting in 2027 and to permit ADUs in all single-family zones with minimal additional requirements.
  • Property owners and developers: Eligible to create or convert units into ADUs on properties with single-family dwellings, subject to the applicable ordinance and state limitations.
  • Home rule municipalities: Limited in how they can regulate ADUs, ensuring consistency with SB4071’s provisions.

Procedural and timeline aspects

  • Effective implementation date: January 1, 2027.
  • Legislative action: Introduced February 24, 2026, with multiple sponsors.
  • Enforcement/limitation: The act serves as a statewide constraint on local zoning powers regarding ADUs, particularly for home rule units.

Practical impact considerations

  • Could significantly increase housing stock and density in single-family neighborhoods by allowing ADUs with minimal new regulatory barriers.
  • May affect neighborhood character discussions, parking demand, and infrastructure planning at the local level, though the bill restricts new regulatory hurdles and parking or size requirements.
  • Encourages use of existing structures for ADUs (e.g., converting garages, attics, basements).

If you’d like, I can tailor this summary to a specific audience (e.g., city planners, housing advocates) or add a comparison with current Illinois Municipal Code provisions.

Compiled from official sources — confirm details with the bill’s official record.

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