Who issues your permit
Each of the roughly 120 cities, villages and towns in suburban Cook County issues its own mechanical permits, so an AC in Bartlett or Lansing is permitted there. Only unincorporated land goes to the County's Department of Building and Zoning. Check which applies in CookViewer with the "Unincorporated Area" layer. The rules below are the County's.
The County's replacement form
The County's building permits page (read 24 October 2026) says all work in unincorporated Cook County needs a permit apart from ordinary repairs and points HVAC work to the HVAC Permit Application for Furnace, Boiler & AC Replacement Only. It asks for:
| Section | What goes in it |
|---|---|
| Contractor and jobsite | HVAC contractor name and Cook County registration number, owner, PIN, where the unit sits (roof, basement, yard) |
| Old and new equipment | Manufacturer, model and AFUE for furnaces and boilers, SEER for condensing units; whether the evaporator coil and refrigerant lines are replaced |
| Cost | Total estimated cost of installation, repair or replacement |
| Conditions you initial | Placement does not block exits or emergency equipment; existing flues, chimney, ducts and gas pipes are verified compatible; fire-rated assemblies are kept intact; new load points are supported |
| Equipment details | Quantity, type, size (BTU or tons) and CFM, and any change to supply or return ductwork |
| Asbestos | Whether any asbestos or asbestos-containing material in the work area will be disturbed |
| Energy | Documents showing the new equipment meets 2018 IECC Section R403.7 for one- and two-family homes |
| Sizing | If capacity changes more than 15% from the old unit, a justification (the form's example: recently upgraded insulation) |
The contractor signs the certification and provides a signed letter of intent.
Who can pull it
The form asks for the HVAC contractor's Cook County registration number. Contractors other than electricians, plumbers and crane operators register under "all other trades": the owner or a corporate officer applies with the firm's incorporation papers and $1,000,000 of general liability insurance; registration is $150, then $75 a year (Contractor Registration). Any wiring is electrical work, which the County reviews separately and which needs a registered electrical contractor whose supervising electrician signs. Homeowners can register and do work themselves if they live in the house and carry $1,000,000 of liability insurance naming Cook County Building and Zoning.
How to apply and what it costs
- Confirm the address is unincorporated and find your 14-digit PIN.
- Email the HVAC application, product sheets and letter of intent to intake.bnz@cookcountyil.gov (25 MB or less), or upload them on the E-Permits portal.
- Pay the $100 residential deposit to start review; it is credited to the final fee.
- Pay the invoice posted to your profile. At issue the County names your field inspectors and the stages they must see.
The County's published fee schedule amendment (effective 1 December 2020) lists no line for furnace or AC replacement, so the invoice sets the fee.
What 10,735 suburban HVAC permits show
From the Assessor's copy of the suburbs' permits (HVAC permits):
| Measure | Suburban Cook County HVAC |
|---|---|
| Permits issued, Jan 2024 to Dec 2025 | 10,735, about 5,368 a year |
| Last 12 months on file (Jan to Dec 2025) | 5,359, about the same as the 5,376 the year before |
| Usual declared value | $9,400 (middle half $6,463 to $13,500) |
| Busiest month / quietest month | July (index 131) / February (75) |
| Filed as "Fireplace-Central Air Conditioning" | 6,966, 65% |
HVAC has two peaks, July and October (119), and January runs slightly above average (103). February and March are the quietest months, the easiest time to book a planned swap. National figures are in HVAC replacement cost, and other cities' rules in do I need a permit to replace my furnace or AC.
Checking the work
Permits already on your address are covered in Cook County building permit search, and Illinois licence lookups in how to check a contractor's license in Illinois. The year and month breakdown is on permit statistics, and individual rows on browse permits.
What this does not tell you
The Assessor's file holds only the permits a suburb reported, names no contractor, has no ZIP code we can publish and no final inspection dates. Village forms and fees differ from the County's.
How we know this
The unincorporated rules are from Cook County Building and Zoning's HVAC Permit Application for Furnace, Boiler and AC Replacement Only (2022), its building permits and Contractor Registration pages, and its fee schedule amendment effective 1 December 2020, all read 24 October 2026. Our counts are the Cook County Assessor's Assessor - Permits file, read 20 October 2026: suburban permits issued January 2024 to December 2025, Chicago excluded.
Numbers come from public permit records in 57 cities, data through October 20, 2026. Nobody paid to be on this page and nobody can.
Questions
- Do I need a permit to replace a furnace or AC in unincorporated Cook County?
Yes. Cook County Building and Zoning has its own HVAC permit application for furnace, boiler and AC replacement, and says all work in unincorporated Cook County needs a permit apart from ordinary repairs. In a city or village, the village's building department issues it.
- What does the Cook County HVAC permit application ask for?
The HVAC contractor's Cook County registration number, the PIN, the make, model and AFUE or SEER of the old and new equipment, whether the coil and refrigerant lines are replaced, the estimated cost, and proof the new equipment meets the 2018 IECC residential energy rules.
- Can I replace my furnace with a smaller or bigger one in Cook County?
On unincorporated land, if capacity changes by more than 15% from the old unit, the County's form asks for a justification, such as recently upgraded insulation.
- How much is an HVAC permit in unincorporated Cook County?
The County's published fee schedule amendment does not list furnace or AC replacement, so the invoice posted after review sets it. A $100 residential deposit is due when you apply and is credited to the fee.
- How many HVAC permits do Cook County suburbs issue?
10,735 from January 2024 to December 2025, as reported to the Cook County Assessor; 5,359 in 2025, about the same as 2024. The usual one declared $9,400, and July is the busiest month.
Build your own list
Pick your city and the kind of work. Every firm with a permit on record, sorted by what you value.
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- HVAC Permit Application for Furnace, Boiler & AC Replacement Only (2022) — Cook County Department of Building and Zoning (2026-10-24)
- Building and Zoning Building Permits — Cook County (2026-10-24)
- Building and Zoning Contractor Registration — Cook County (2026-10-24)
- Assessor - Permits (6yjf-dfxs) — Cook County Open Data (2026-10-20)