Illinois Building Codes, Permits and Contractor Rules
Here’s every rule from our 50-state guides for Illinois on one page: the residential building code, frost depth, retaining wall permits, the 811 dig law, drainage law, contractor licensing, deposit limits, mechanics lien deadlines, workers’ comp, planting zones and frost dates. Each section links the official source and the full 50-state comparison.
Illinois at a glance
- Building code: Set by cities and counties
- Frost depth: Set locally; often 36-42 in.
- 811 notice: At least 2 days but no more than 10 days before excavation (weekends, holidays and the day of the request not counted)
- Contractors: No statewide requirement (local)
- Deposits: No statewide cap
- Liens: 4 months after completion (90-day sub notice)
- Workers’ comp: 1+ employees
- Drainage rule: Civil law (natural flow)
- Planting zones: 5a to 7b
| Topic | Illinois | Compare |
|---|---|---|
| Residential building code | Set by cities and counties | All states |
| Frost line depth | Set locally; often 36-42 in. | All states |
| Retaining wall permit | Set locally | All states |
| 811 notice before digging | At least 2 days but no more than 10 days before excavation (weekends, holidays and the day of the request not counted) | All states |
| Contractor license | No statewide requirement (local) | All states |
| Deposit limit | No statewide cap | All states |
| Right to cancel | 3 bus. days (15 if 65+), sales at home | All states |
| Lien filing deadline | 4 months after completion (90-day sub notice) | All states |
| Workers’ comp required | 1+ employees | All states |
| Drainage between neighbors | Civil law (natural flow) | All states |
| Planting zones (2023 USDA) | 5a to 7b | All states |
| Frost dates (NOAA) | Last frost early Apr (Cairo) to late Apr (Rockford); first frost mid-Oct (Rockford) to late Oct (Cairo) | All states |
Illinois residential building code
- Code
- No statewide residential code; cities and counties adopt their own (often a recent IRC)
- How it applies
- Local adoption (no statewide residential code)
- Code agency
- None for residential construction
- Who enforces it
- In areas with no building code, a new-home contract must name the IRC or a local code within 100 miles; if it names none, the current IRC applies by law.
- Good to know
- Illinois has no statewide house code. Where your town or county has no code, Illinois law makes the current IRC the default standard in a new-home contract.
Compare building codes in all 50 states
Frost line depth in Illinois
- Who sets it
- Local building department
- Local examples
- City of Joliet: 42 in.
City of Peoria: 36 in.
City of Rock Island: 42 in. - Typical range
- 36-42 in.
- Good to know
- Chicago Municipal Code 13-132-100 requires footings 42 in. (3 ft 6 in.) below grade, but that is older Title 13 text, so confirm it under the current Chicago Construction Codes.
Frost line depth in every state
Retaining wall permits in Illinois
- Permit exemption
- Set locally
- Who decides
- Your municipality or county decides. In areas without a building code, the construction contract sets the code.
- Good to know
- In areas without a building code, a new-home construction contract must adopt the IRC or a local code, and the current IRC is the default. For a retaining wall, check with your municipality or county.
Retaining wall permit rules in every state
811 dig law in Illinois
- One-call center
- JULIE, Inc. (outside Chicago) / 811 Chicago (DIGGER, City of Chicago)
- Notice before digging
- At least 2 days but no more than 10 days before excavation (weekends, holidays and the day of the request not counted)
- Ticket good for
- 25 days including the day of the request (extensions requested between day 20 and 25)
- Hand-dig zone
- 18 in. on either side of a marked line
- Homeowners
- Yes. JULIE says to call for 'every project, every time… regardless of the depth or the size of the project,' including planting trees and shrubs. JULIE states no homeowner, hand-tool or depth exemption.
- The law
- 220 ILCS 50/1 et seq. (Illinois Underground Utility Facilities Damage Prevention Act)
- Good to know
- JULIE asks homeowners to call at least 3 days ahead, though the legal minimum is 2 days not counting the day you call. Chicago has its own center, 811 Chicago.
Drainage law and stormwater permits in Illinois
- Rule
- Civil law (natural flow)
- The rule
- Modified civil law: the upper owner has an easement for natural drainage but is liable for increasing the flow beyond what nature would produce; reasonable development is allowed ('good husbandry'), and in urban and suburban settings courts apply a reasonableness balancing test.
- Leading case
- Templeton v. Huss (as applied in Shulte v. Flowers). Templeton v. Huss, 57 Ill. 2d 134 (1974); Shulte v. Flowers, Ill. App. Ct. 4th Dist. No. 4-12-0132 (Feb. 8, 2013)
- What it means for your yard
- Natural runoff onto a lower lot is allowed, and reasonable improvements are too, but if your regrading, downspouts or patio unreasonably increase the water reaching a neighbor, especially in a town or subdivision, you can be liable.
- Construction stormwater permit
- Illinois Environmental Protection Agency (Illinois EPA), Bureau of Water: 1 acre or more of disturbance: General NPDES Permit for Construction Site Activities (ILR10); under the federal rule, smaller sites that are part of a larger common plan of 1 acre or more are also covered
- State rules below 1 acre
- No statewide rule below the 1-acre permit found; check your county and town.
- Local rules
- Illinois counties and municipalities often require stormwater or grading permits for smaller residential projects.
- Good to know
- Illinois allows natural runoff and reasonable improvements, but in towns and subdivisions courts ask whether an increase in runoff onto a neighbor was reasonable. State construction stormwater permits start at 1 acre.
Contractor licensing in Illinois
- Statewide rule
- No statewide requirement (local)
- Who needs it
- No statewide general or home improvement contractor license; roofing contractors need a state roofing license.
- Licensed separately
- Roofing contractors are licensed by the state under the Illinois Roofing Industry Licensing Act.
- Good to know
- Local licensing varies by city, so check with your city or village before you hire.
Contractor license requirements in every state
Contractor deposits and your right to cancel in Illinois
- Deposit limit
- No statewide cap. If the contractor fails to start or finish on time, the homeowner may cancel and may be entitled to a refund of the down payment and other payments on written demand by certified mail (815 ILCS 513/20 pamphlet).
- Right to cancel
- Contracts signed at home: 3 business days. Homeowners 65 or older who buy home repair or remodeling services from an uninvited solicitor at their home: 15 full business days after signing (815 ILCS 513/22). Insurance-funded work: if the insurer denies all or part of the claim, the homeowner may cancel by written notice before the earlier of midnight of the fifth business day after receiving the insurer's notice or the thirtieth business day after the insurer receives proof of loss, and payments are returned within 10 business days (815 ILCS 513/20 pamphlet).
- Written contract
- Contractors must give the 'Home Repair: Know Your Consumer Rights' pamphlet; for contracts over $1,000 the homeowner signs an acknowledgment and has the right to a written contract listing the contractor's name, address and phone, description of work, start and estimated completion dates, total cost, the payment schedule including down payment, and termination terms (815 ILCS 513/20).
- Other protections
- Refund of down payment if the contractor fails to begin or complete on time (815 ILCS 513/20).
- The law
- Home Repair and Remodeling Act, 815 ILCS 513/20, 513/22; Consumer Fraud Act 815 ILCS 505/2B (home sales)
- Good to know
- Illinois homeowners 65 and older get 15 business days to cancel a home repair contract sold by a contractor who showed up uninvited. Starting work does not take away your right to cancel.
Contractor deposit limits in every state
Mechanics lien deadlines in Illinois
- Lien deadline (prime)
- Record a claim for lien within 4 months after completion to bind third parties such as lenders and buyers; against the owner, within 2 years after completion of the contract (770 ILCS 60/7). On an owner-occupied single-family residence, give the owner written notice within 10 days after recording (60/7(d)).
- Lien deadline (sub/supplier)
- Serve the 90-day notice (60/24); then a claim for lien or suit follows the Sec. 7 and Sec. 9 time limits (770 ILCS 60/28).
- Preliminary notice (sub/supplier)
- Notice of claim to the owner within 90 days after completing its work (770 ILCS 60/24). On an owner-occupied single-family residence, also notify the occupant within 60 days after first furnishing; later notice preserves the lien only to the extent the owner was not prejudiced by payments made before receiving it (770 ILCS 60/21(c)).
- Notice of intent
- Not required.
- Enforce within
- Suit within 2 years after completion of the contract (770 ILCS 60/9), or within 30 days after a written demand from the owner or another interested party, or the lien is forfeited (60/34).
- Homeowner rules
- The owner generally can't be made to pay more than the contract price unless subs gave notice (770 ILCS 60/21(d)). Payments made without getting the contractor's sworn statement are not protected against subs (60/5, 60/32). On an owner-occupied single-family home, the contractor must notify the owner within 10 days after recording a lien (60/7(d)).
- The law
- Mechanics Lien Act, 770 ILCS 60/0.01 et seq.
- Good to know
- Illinois subcontractors on an owner-occupied single-family home should notify the homeowner within 60 days of starting, not just the 90-day notice after finishing. Homeowners should get the contractor's sworn statement before each payment.
Mechanics lien deadlines in every state
Workers' comp requirements in Illinois
- Who must carry it
- Any employer with 1 or more employees, even part-time, must carry coverage, with rare exceptions; extra-hazardous work under Section 3, which includes construction, must be covered, and the Employee Classification Act (820 ILCS 185) requires construction businesses to insure in almost all cases (820 ILCS 305/3, 305/4; IWCC).
- Owners and officers
- Sole proprietors, partners, corporate officers and LLC members are generally not required to cover themselves; to come under the Act they buy insurance for themselves, and to opt out of a policy that covers other employees they notify their insurer in writing. The IWCC has no opt-out form (IWCC).
- Subcontractors
- A business doing Section 3 work (which includes construction) that contracts any of it out is liable for compensation to the employees of a contractor or sub that hasn't insured, and can recover what it pays from that contractor; this applies only to injuries on or about the premises where the principal contracted for the work to be done (820 ILCS 305/1(a)(3)).
- Penalties
- Knowing and willful failure to insure: fines up to $500 per day with a $10,000 minimum, and a stop-work order halting all business operations until proof of insurance; negligent failure is a Class A misdemeanor and knowing failure a Class 4 felony; officers can be personally liable; injured workers can sue an uninsured employer in civil court (820 ILCS 305/4(d); IWCC).
- The law
- 820 ILCS 305 (Workers' Compensation Act); §§ 1(a)(3), 3, 4(d)
- State agency
- Illinois Workers' Compensation Commission
- Good to know
- Illinois requires coverage with even one part-time employee, and construction work is always covered. Willfully going without coverage can mean a stop-work order and fines of at least $10,000.
Workers' comp requirements in every state
Planting zones in Illinois
- 2023 USDA zones
- 5a to 7b
- Coldest-night range
- −20°F to 10°F
- Coldest area
- Northwestern Illinois
- Warmest area
- Southern tip of the state
- Example cities
- Chicago: 6b, Rockford: 5b, Peoria: 6a, Carbondale: 7a
- Local plant advice
- University of Illinois Extension
- Good to know
- Illinois gained its first zone 7b area, a small sliver at the southern tip. The line between zones 5b and 6a moved roughly 60 miles north, from around Springfield to around Peoria.
Frost dates in Illinois
| Station | Last spring frost | First fall frost | Frost-free days |
|---|---|---|---|
| Chicago Northeast Illinois (O'Hare airport station) | April 16 | October 28 | 193 |
| Rockford Northern Illinois | April 24 | October 17 | 174 |
| Springfield Central Illinois | April 14 | October 20 | 187 |
| Cairo Southern tip | April 2 | October 31 | 211 |
- Typical range
- Last frost early Apr (Cairo) to late Apr (Rockford); first frost mid-Oct (Rockford) to late Oct (Cairo)
- Good to know
- These are typical (50%) dates from NOAA's 1991–2020 climate normals, so about half of years still bring a 32°F night after the listed spring date. In Illinois, the last spring frost at the stations listed ranges from early April around Cairo to late April around Rockford.
- Local frost or planting guide
- University of Illinois Extension
Frequently Asked Questions
What building code does Illinois use?
No statewide residential code; cities and counties adopt their own (often a recent IRC). It applies as follows: local adoption (no statewide residential code). Your local building department can confirm the edition and amendments for your address.
How deep is the frost line in Illinois?
Frost depth is set by local building departments. Typical local values: 36-42 in.. Footings for houses, additions and attached decks go below it.
How much can a contractor ask for up front in Illinois?
No statewide cap. If the contractor fails to start or finish on time, the homeowner may cancel and may be entitled to a refund of the down payment and other payments on written demand by certified mail (815 ILCS 513/20 pamphlet). Cancel rights: Contracts signed at home: 3 business days. Homeowners 65 or older who buy home repair or remodeling services from an uninvited solicitor at their home: 15 full business days after signing (815 ILCS 513/22). Insurance-funded work: if the insurer denies all or part of the claim, the homeowner may cancel by written notice before the earlier of midnight of the fifth business day after receiving the insurer’s notice or the thirtieth business day after the insurer receives proof of loss, and payments are returned within 10 business days (815 ILCS 513/20 pamphlet).
How long does a contractor have to file a mechanics lien in Illinois?
Record a claim for lien within 4 months after completion to bind third parties such as lenders and buyers; against the owner, within 2 years after completion of the contract (770 ILCS 60/7). On an owner-occupied single-family residence, give the owner written notice within 10 days after recording (60/7(d)). Subcontractors and suppliers may have different notice rules; see the section above.
What planting zone is Illinois?
On the 2023 USDA map, Illinois runs from zone 5a to 7b. Examples: Chicago 6b, Rockford 5b, Peoria 6a. Enter your ZIP on the USDA map for your exact zone.
Do contractors need workers' comp in Illinois?
Any employer with 1 or more employees, even part-time, must carry coverage, with rare exceptions; extra-hazardous work under Section 3, which includes construction, must be covered, and the Employee Classification Act (820 ILCS 185) requires construction businesses to insure in almost all cases (820 ILCS 305/3, 305/4; IWCC). Owner exemptions and subcontractor rules are in the workers’ comp section above.
When is the last frost in Illinois?
At the NOAA stations we list: Last frost early Apr (Cairo) to late Apr (Rockford); first frost mid-Oct (Rockford) to late Oct (Cairo). These are typical (50%) dates from the 1991–2020 climate normals, so about half of years still bring a 32°F night after the spring date.
This page is general information, not legal or tax advice. Rules change; the agencies and statutes linked above have the final word.
Illinois in each 50-state guide: Frost line depth · 811 dig laws · Retaining wall permits · Contractor licensing · Contractor deposit limits · Building codes · Planting zones · Mechanics lien deadlines · Workers' comp · Frost dates · Drainage laws · Noxious weed laws · Rainfall and snowfall · Landscaper pay · Pesticide applicator licensing · Landscaping sales tax · All state guides
Soil: Illinois’s most common soils, state soil, and how much ground is wet, clayey or shallow to bedrock by county. Illinois soil types
Last checked October 31 and November 1, 2026 against official state and local sources for this state. Rules change; your state agency or local building department has the final word. Spot something out of date? Email info@muthlerlandscaping.com and we’ll fix it.
Groundwork Design Co. · designed by builders
Plans drawn for Illinois’s rules
Groundwork Design Co. draws patios, walls, decks and planting plans to scale for any U.S. home, with the layout, sizes and materials any local contractor can price. Single-space plans start at $349; a framing and footing sheet for decks and porches is a $350 add-on.
Using this guide? Link to it or cite it. It’s free to use with a link back, and we keep it updated against official sources.
Cite as: Muthler Landscaping & Construction, “Illinois Building Codes, Permits and Contractor Rules,” https://muthlerlandscaping.com/state-guides/illinois/ (last checked November 12, 2026).
Get an email when your state’s rules change
We re-check every entry against official sources. Tell us your state and we’ll email you when something changes.