1. Call JULIE before anyone digs
JULIE is the state's free one-call service for marking buried utility lines. Its homeowner page names building a deck as a project that needs underground lines marked.
- Who calls: the person actually digging. If your builder digs the footings, the builder makes the call. If you dig them yourself, you call. JULIE FAQ
- When: at least 3 days before digging, and weekends and holidays do not count. Your ticket shows the date digging may start. JULIE for homeowners
- How: call 811 or (800) 892-0123, or file online any time. The service is free.
- Mark the spot: outline where you will dig in white paint or flags (black if there is snow).
- What it does not cover: utilities do not mark lines you own yourself, such as sprinkler pipes or yard-light wiring.
2. Permits are local
There is no statewide deck permit. Each city, village or county decides what it needs. Every city we checked requires a permit for a typical new deck attached to a house. Small exemptions exist: Rockford exempts a one-story detached deck of 120 square feet or less, and Decatur asks for a permit only when a deck is over 200 square feet, more than 30 inches above grade, attached to the house, or serves a required exit.
Most towns ask for a drawing of the deck and where it sits on the lot. Joliet wants a plat of survey with the deck marked, and plans showing joists, posts, beams, the ledger board and the guardrail. Elgin wants a plat of survey or site plan. Chicago sends deck work through plan review, with plans by an Illinois-licensed architect or structural engineer. In Joliet, if a contractor does the work, the contractor must pull the permit.
We have looked up the rules for 20 cities: deck permit rules by city.
Sources: City of Rockford, City of Joliet, City of Elgin, City of Chicago, and each city's page on our permit pages
3. Footings and inspections
There is no statewide footing depth. Across northern Illinois, the cities we checked use 42 inches. Rockford sets frost footings at 42 inches below grade. Naperville, Elgin, Schaumburg, Evanston and Chicago set deck piers or footings at 42 inches. Joliet wants 42 inches for a deck attached to the house and 24 inches for a free-standing one, and Elgin also exempts decks not attached to the building from its 42-inch rule. Further south the figure drops: Bloomington's code uses 40 inches and Decatur's 36.
Expect the town to look at the holes before concrete goes in. Rockford inspects footings before they are poured and framing before it is covered. Ask your builder to schedule the inspections, and do not let anyone pour until the footing inspection passes.
Sources: City of Rockford, Naperville deck guide, Elgin deck guide, Chicago porch and deck guidelines
4. Railings
Naperville, Elgin, Joliet, Schaumburg and Bolingbrook require a guardrail once a deck is about 30 inches above the ground, at least 36 inches high. Naperville and Joliet also limit the gaps between balusters to 4 inches. Chicago's guidelines are stricter: guards at least 42 inches high on porches and decks two feet or more above grade.
Sources: Naperville deck guide, City of Joliet, Chicago porch and deck guidelines
5. The written contract rule
The Illinois Home Repair and Remodeling Act (815 ILCS 513) covers work on a home with six or fewer units, and names porches in its list of covered work.
- Over $1,000, the company must give you a written contract or work order to sign before work starts. It must list the total cost with materials, any charge for the estimate, and the company's business name and address.
- The company must give you the state pamphlet "Home Repair: Know Your Consumer Rights". On jobs over $1,000 you sign a form saying you got it. The Attorney General posts it in English, Spanish and Polish.
- If you are 65 or older and signed at home with a salesperson who came uninvited, you can cancel within 15 full business days.
Source: 815 ILCS 513, Illinois General Assembly
6. Insurance and licenses
The same Act requires home repair companies to carry liability and property damage insurance, unless the company has a net worth of at least $1,000,000. The state does not require them to show you proof, so ask for a certificate of insurance before work starts.
Illinois does not license general contractors at the state level. The Attorney General says so directly, and notes that cities and villages may have their own requirements. Some towns register contractors, so ask which registration a "licensed" builder means.
Source: Illinois Attorney General
7. Warning signs from the Attorney General
- Be wary of contractors who knock on your door offering work or "free" inspections.
- Never pay in cash or by Venmo or Zelle.
- Never pay in full until the work is done to your satisfaction.
- Get several written estimates, and do not be rushed.
- Never sign a contract with blank spaces.
- Ask for a sworn statement listing subcontractors before you pay, so nobody can put a lien on your home for an unpaid bill.
To report a problem, the Attorney General's consumer fraud hotlines are Chicago (800) 386-5438, Springfield (800) 243-0618 and Carbondale (800) 243-0607.
Source: Illinois Attorney General, home repair
This page explains what public sources say. It is not legal advice, and we are not a government agency. Rules change; check with your town before you build.