The Indiana Mechanical Code is the set of rules governing how heating, cooling, ventilation, refrigeration, and related systems are designed, installed, and maintained in buildings across the state. Indiana currently enforces the 2014 edition, which is built on the 2012 International Mechanical Code with state-specific amendments that took effect December 1, 2014. If you are replacing a furnace, adding central air, installing a boiler, or putting in commercial exhaust, your project has to meet it, and in almost every case you need a permit from your local building department before the work starts.
What the Code Covers
The code reaches nearly every system that conditions or moves air inside a building: central heating, air conditioning, ventilation and exhaust, ductwork, and the combustion air supply fuel-burning appliances need to operate safely.1UpCodes. Indiana Mechanical Code, 2014 Edition It also covers refrigeration equipment, hydronic piping, and solar thermal installations. Chimneys, vents, fireplaces, and solid-fuel appliances like wood stoves have their own chapters with clearance and venting rules, and boilers, water heaters, and pressure vessels are handled separately as well.2Legal Information Institute. Indiana Code 675 IAC 18-1.6 – 2014 Indiana Mechanical Code The rules apply to both residential and commercial buildings.
Who Adopts It and Who Enforces It
Indiana does not write its mechanical code from scratch. The Indiana Fire Prevention and Building Safety Commission adopts the International Mechanical Code as a base and layers Indiana amendments on top through the Indiana Administrative Code at 675 IAC 18. Where the state amendments conflict with the model code, the Indiana amendments control.2Legal Information Institute. Indiana Code 675 IAC 18-1.6 – 2014 Indiana Mechanical Code
Enforcement happens at your local building department. One detail catches people off guard: Indiana law prohibits cities, towns, and counties from adopting mechanical requirements that are stricter than what the commission has set. A local jurisdiction can enforce the state code, but it cannot add to it.
When You Need a Mechanical Permit
Most mechanical work that installs, replaces, or substantially alters heating, cooling, or ventilation equipment needs a permit. That includes a new furnace, a central air system, new ductwork, a boiler, and commercial exhaust.
Some lower-risk work is exempt. Indianapolis, for example, exempts replacing a water heater with an identical unit that matches the original’s venting arrangement and fuel type, and it exempts extending existing heating or cooling ductwork.3City of Indianapolis. Residential Development Permits The base International Mechanical Code also generally exempts portable heating and cooling appliances and minor part replacements that do not change how the equipment was originally approved. Rules vary from one city to the next, so confirm with your local department before you start. Checking in advance is always cheaper than resolving a violation afterward.
What to File and What It Costs
Applications go to your local building department, online or in person. The forms differ by jurisdiction, but the information you will need to provide is consistent across the state. For a typical residential project, expect to supply:
- The project address and a clear work description, such as replacing a gas furnace or installing a split-system heat pump.
- Equipment specifications, including manufacturer model numbers, BTU input and output ratings, and efficiency ratings like SEER2 for cooling equipment. The manufacturer’s spec sheet speeds this up.
- Mechanical drawings or floor plans showing equipment placement, ductwork routing, and exhaust venting. Simple replacements may require less detail than new installations.
- Contractor information, including a local license number where the municipality requires one, and proof of insurance.
- Fuel type and venting details: natural gas, propane, electric, or oil, and how combustion byproducts will be vented.
- A project cost estimate for labor and materials, which some jurisdictions use to calculate the fee.
Fees vary. Some Indiana communities charge flat fees as low as $30 for a straightforward residential HVAC replacement, while larger or commercial jobs cost more. Ask your building department for the current fee schedule before you submit.
Review, Rough-In, and Final Inspection
After you file and pay, code officials review the work against 675 IAC 18.2Legal Information Institute. Indiana Code 675 IAC 18-1.6 – 2014 Indiana Mechanical Code Standard residential reviews typically run from a few business days to around two weeks, depending on department workload. Commercial projects take longer. Keep the permit posted at the job site until the project is closed out.
When the work is finished, schedule an inspection. The inspector verifies the installation matches the approved plans and meets code. One point that trips up first-timers: do not close up walls, ceilings, or chases before the rough-in inspection. The inspector needs to see ductwork, flue connections, and internal components before they are concealed.4Brown County, IN. Building Department If the installation passes, the department issues a certificate of completion or occupancy. If it does not, you will get a correction notice, make the fixes, and schedule a reinspection. The permit stays open until the department signs off.
What Happens If You Skip the Permit
Working without a permit rarely pays off. If a code official finds unpermitted mechanical work, the building department can issue a stop-work order that halts the entire project. Fines vary by jurisdiction but can reach $2,500 or more per violation, and some communities treat each day the violation continues as a separate infraction. Many jurisdictions also charge a surcharge on top of the normal permit fee when you apply after work has already begun, often double or triple the standard amount.
The follow-on problems can be worse. Unpermitted work complicates a home sale because buyers’ inspectors and title companies flag the missing paperwork. Your homeowner’s insurer may deny a claim tied to unpermitted mechanical work, leaving you personally responsible for fire or water damage.
Does Your Contractor Need a State License?
Indiana does not issue a state-level HVAC contractor license. Licensing is handled locally, and each municipality decides whether to require one at all.5City of Indianapolis. Contractor Licenses Indianapolis requires HVAC contractors to pass an exam and get approval from a local licensing board before they install or repair heating and cooling equipment. Other communities have no licensing requirement.
That patchwork matters when you hire someone. In a city with licensing, your contractor needs a license for that specific jurisdiction. In a community without licensing, the only credential check usually happens through the permit process. Either way, confirm the contractor carries general liability insurance and workers’ compensation coverage. A permit alone does not guarantee the installer is qualified.
Equipment Efficiency Minimums
Any heating or cooling equipment installed in Indiana must meet or exceed the federal minimum efficiency standards set by the Department of Energy. Since January 1, 2023, those standards use the updated SEER2 and HSPF2 testing protocols. Indiana sits in the DOE’s North region, where the current minimums are:
- Central air conditioners, split system: 13.4 SEER2
- Heat pumps, split system: 14.3 SEER2
Equipment below these minimums cannot legally be installed and will not pass inspection. When you gather specifications for your application, confirm the rated efficiency clears the threshold. Most current equipment from major manufacturers already complies, but older stock sitting in a warehouse may not.
Rebates That Can Offset the Cost
If you are installing high-efficiency equipment, check the available incentives before locking in a budget. The Indiana Office of Energy Development launched the Indiana Energy Saver Program on May 14, 2025, and applications are currently open.6Indiana Office of Energy Development. OED: Home Energy Rebates The program channels federal Inflation Reduction Act funding into point-of-sale rebates for qualifying home energy upgrades, including heat pump installations. Eligibility and rebate amounts are tied to household income relative to area median income, with lower-income households qualifying for larger rebates.
One incentive is no longer available for new work: the federal Energy Efficient Home Improvement Credit under Section 25C, which provided up to $2,000 per year for qualifying heat pumps and up to $1,200 for other efficient HVAC equipment, expired for property placed in service after December 31, 2025.7Office of the Law Revision Counsel. 26 USC 25C – Energy Efficient Home Improvement Credit Equipment installed in 2025 or earlier can still be claimed on the relevant return, but installations in 2026 do not qualify. For new projects, look to the Indiana Energy Saver Program and any utility company rebates in your area.