ADU Pass
Joliet
Will County portion
Also in: No County
ADU Pass helps homeowners in Joliet, Will County, Illinois navigate the permit paperwork for building an accessory dwelling unit. This area covers 7 ZIP codes.
Map
ADU details
ADU legality: unclear
Illinois leaves ADU regulation to local municipalities under home-rule or Dillon-rule authority. Joliet permits ADUs subject to local conditions per its zoning ordinance.
Cost scenarios
| Scenario | Sq ft | Permit | Build | Total |
|---|---|---|---|---|
| minimum | 150 | $2,400 | $42,750 | $45,150 |
| 600 | 600 | $2,400 | $171,000 | $173,400 |
| midpoint | 525 | $2,400 | $149,625 | $152,025 |
| maximum | 900 | $2,400 | $256,500 | $258,900 |
Fee breakdown
Viability (permitted uses)
- Long-term rental: yes Long-term rental of ADU generally permitted; landlord-tenant law and any city rental-registration ordinance apply.
- Short-term rental: with-restrictions STR rules vary by city. Joliet regulates STRs separately from ADU permitting; check local STR ordinance and HOA covenants.
- Office rental: with-restrictions Detached office rental requires home occupation permit or rezoning.
- Home office: yes Home occupation permitted with restrictions on signage and customer traffic.
- Studio / workshop: yes Personal artist studio is a permitted accessory use.
- Agriculture: with-restrictions Limited urban agriculture permitted in residential zones; livestock varies by district.
- Relative support: yes Family-occupancy ADU explicitly permitted in single-family zones.
Utilities
- Water: Joliet Water Utility · 30d connect · $4,500
- Sewer: Joliet Sewer / Wastewater · 30d connect · $5,500
- Electric: Joliet Electric Utility · 21d connect · $1,800
- Gas: Joliet Gas Utility · 30d connect · $1,500
Property values & taxes
Construction timeline
Realistic total: best 7mo · typical 10mo · worst 16mo
Financing
State ADU loans:
Insurance impact
HOA prevalence & preemption
Illinois has no HOA-ADU preemption; HOA covenants restricting ADUs are enforceable.
Technical envelope (climate & building code)
Climate & energy code
Building code
Amendments:
- Amendment
- Amendment
Legal history (timeline)
Current ordinance: City of Joliet Municipal Code — Accessory Dwelling Units, adopted 2020-01-01, last amended 2024-04-01
- 2024-01-01 — City of Joliet ADU code refresh (city-ordinance)
Conforming local-code amendments aligning with current Illinois accessory-dwelling framework.
Effect: Codified permissive ADU standards consistent with state law and local zoning.
Will County — county ADU rules and overlays
County ADU ordinance
Will County, Illinois - 696,000 residents in the south-southwest exurban Chicago area - regulates accessory dwelling units in unincorporated territory through the Will County Zoning Ordinance, administered by the Will County Land Use Department. Will is a fast-growing exurban county with substantial unincorporated territory; incorporated cities include Joliet (largest), Bolingbrook-portion, Romeoville, Plainfield, Crest Hill, Lockport, Frankfort, Mokena, New Lenox, Tinley Park-portion, Channahon, Wilmington. Each incorporated municipality sets its own ADU rules under home-rule authority where applicable.
State-floor overlay: Illinois has not enacted statewide ADU preemption.
County regulatory overlays
Will County administers flood-hazard, and (where mapped) coastal, wildland-fire, historic, and airport overlays that shape ADU project feasibility. The most consistent overlay across the county is FEMA NFIP floodplain regulation; other overlays apply to specific geographies inside the county.
- FEMA NFIP Special Flood Hazard Areas in Will County — A new ADU in a mapped SFHA must be elevated to or above the Base Flood Elevation; cost impact on the project is often material.
- Historic districts and individually-listed historic resources
County permitting (unincorporated parcels)
Will County issues building permits for parcels in unincorporated territory through its development services / planning department, with separate review tracks for zoning conformance, building-code compliance, on-site sewage where applicable, floodplain compliance, and addressing. Inside incorporated municipalities, city departments handle their own permits; the county's authority is geographically limited to unincorporated territory. An ADU permit application is typically processed as a residential building permit with a zoning verification step against the county's ordinance for the parcel's zoning district.
Illinois state — ADU law and programs
State financing programs
Illinois does not operate an ADU-specific statewide loan, grant, or forgivable-loan program. The Illinois Housing Development Authority (IHDA) is the state's housing finance agency and administers a robust portfolio of homebuyer products: Access Forgivable, Access Deferred, Access Repayable down-payment-assistance variants, the IHDA Mortgage first-mortgage product, and the federal Low-Income Housing Tax Credit allocation. The 2025 IHDA Access Home program offers DPA equal to 6% of purchase price up to $15,000. None target ADU construction directly; an ADU-bearing primary residence on an Illinois lot can qualify for the underlying mortgage when other criteria are met.
Federal (United States) — ADU-relevant rules and programs
Federal ADU law
The United States has no federal statute that directly regulates accessory dwelling unit entitlement or design. Land-use authority over ADUs resides with states and local governments under the traditional police power. Federal engagement is limited to financing (Fannie/Freddie/FHA/VA/USDA), flood insurance (FEMA/NFIP), and discretionary housing programs (HUD), which are recorded in sibling sections of this file.
Federal financing programs
Federal housing-finance agencies and GSEs set nationwide underwriting rules that govern whether an ADU can be financed, appraised, and counted toward mortgage qualifying income. The relevant actors are Fannie Mae, Freddie Mac, FHA (HUD), VA, and USDA Rural Development.
Federal tax credits
There is no ADU-specific federal tax credit. ADUs may incidentally qualify for existing federal energy-efficiency and clean-energy tax credits when the ADU construction includes qualifying measures.
Federal housing programs
HUD administers several discretionary programs that can fund ADU-related activity at the grantee's election, but none is an ADU-specific program.
ZIP Codes
- 60403
- 60404
- 60431
- 60432
- 60433
- 60435
- 60436
Post Office
- 2000 Mcdonough St, 60436