ADU Rules in Chicago, IL (2026)
ADU rules, permit requirements, size limits, and fees for Chicago, IL. Source-cited from official municipal code.
Whether ADUs are allowed in Chicago, IL has not been confirmed — see the official source before proceeding.
Whether Chicago, IL permits accessory dwelling units (ADUs) has not been confirmed from an official source. ADUs — also called granny flats, in-law units, or secondary suites — are secondary housing units on a single-family or multifamily lot. Contact the local building department at (312) 744-3449 to verify current ADU rules before proceeding, as regulations may have changed since this data was last reviewed.
ADU Size Limits
ADU Size Limits in Chicago: Detached ADU: size varies by zoning — see official source (max height: 22 feet). Attached ADU: size varies by zoning — see official source.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | See official source | 22 feet · Verified July 14, 2026 · Source |
| Attached ADU | See official source | See official source |
Permit Fees
ADU Permit Fees in Chicago: Plan check fee: Varies. Building permit fee: Varies. Impact fees: None. School fees: None or N/A. Total estimated permit cost: Varies.
| Fee Type | Amount |
|---|---|
| Plan Check | None |
| Building Permit | None |
| Impact Fees | None |
| School Fees | None |
| Total Estimate | See official source |
Permit Timeline
Chicago ADU Permit Timeline: Permit timeline has not been confirmed — contact the department for current processing times. Apply through the local building department online permit portal. Phone: (312) 744-3449.
Setback Requirements
ADU Setback Requirements in Chicago: Front setback: follows zone standard. Side setback: no minimum. Rear setback: no minimum.
Parking Requirements
Parking Requirements: Parking requirements have not been confirmed — see official source.
Restrictions & Requirements
- Owner-occupancy required only where the principal building adding a conversion unit or coach house is a detached house — that detached house must be owner-occupied at the time of pre-certification. Applies only within the designated RS Areas, not citywide.
- See official source
- See official source
- See official source
- See official source
- See official source
How Many ADUs Are Allowed?
Number of ADUs Allowed in Chicago: Single-family lots: not confirmed — see official source. Multifamily properties: not confirmed — see official source.
- Single-Family Lots
- See official source
- Multifamily Properties
- See official source
Statewide Preemption
ADU Preemption
Illinois's official source could not be reached to confirm statewide ADU preemption.
View Illinois preemption detailsFrequently Asked Questions
Can I build an ADU in Chicago?
Yes. Chicago, IL allows accessory dwelling units.
How big can an ADU be in Chicago?
The maximum size for a detached ADU in Chicago is 1,000 square feet.
How long does it take to get an ADU permit in Chicago?
The typical ADU permit timeline in Chicago is Chicago DPD building permit for ADU: typically 3-6 months for plan review. ADU Express program in development. Construction 4-12 months.. Total estimated permit fees are $1,500–$6,500 total permit fees.
Do I need extra parking for an ADU in Chicago?
Chicago parking rules for ADUs: No replacement parking required when garage is converted to ADU. New detached ADUs (coach houses) typically built over new 1-car garage — no additional parking required per ADU Ordinance.
Do I have to live on-site to have an ADU in Chicago?
Owner-occupancy requirement in Chicago: Owner-occupancy applies only where the principal building on the zoning lot adding a conversion unit or coach house is a detached house — that detached house must be owner-occupied at the time of pre-certification.
Official source document could not be verified — see the citation link for the current code.. Last verified April 3, 2026. See official source