Permit Required? Required
Typical Fee Range $100–$300 Standard residential flat fee for system replacement.
Fee Method Flat fee
Apply Online Apply at Buildings, Safety Engineering, and Environmental Department →

What's Required in Detroit

  • Mechanical permit required for all HVAC unit replacements.
  • Manual J load calculations required for new system sizing.
  • Electrical permit mandatory for power connections to the unit.
  • Proper venting and condensate drainage must be installed.
  • Exterior unit must meet property line setbacks and noise codes.
  • Gas piping permit required if switching from electric to gas heat.

Do You Need a Permit to Replace an AC or Furnace in Detroit?

Yes. Detroit treats HVAC replacement as permit-required work, and that includes the common case people hope is exempt: a like-for-like swap of a furnace, AC condenser, or heat pump in the same location. Permit fees typically run $100–$300, and the permit is issued by the Buildings, Safety Engineering, and Environmental Department. In practice your HVAC contractor pulls it as part of the job — if a bid doesn't mention the permit, ask why, because unpermitted mechanical work surfaces at home sale time and in insurance claims.

HVAC Repairs vs. Replacement: Where the Permit Line Falls

The line falls at equipment, not maintenance. Repairs that keep an existing system running — a blower motor, capacitor, control board, or a thermostat swap on existing wiring — generally don't need a permit. Replacing the equipment itself, adding or reworking ductwork, or running new gas or electrical almost always does. Refrigerant-line and coil replacements sit in the gray zone and vary by city. When the scope is unclear, describe the exact job to the Buildings, Safety Engineering, and Environmental Department before work starts; it's a five-minute call.

How to Get a HVAC Permit in Detroit

1

Step 1: System Sizing

Perform load calculations to select the correct unit size.

2

Step 2: Apply Online

Contractors file for mechanical and electrical sub-permits.

3

Step 3: Installation

Replace the furnace/condenser according to mechanical code.

4

Step 4: Safety Check

Ensure all gas and electrical connections are secure.

5

Step 5: Final Inspection

Inspector checks drain lines, safety switches, and performance.

Frequently Asked Questions

Yes, any permanent HVAC installation requires a permit.
Minor component repairs generally do not require a mechanical permit.
Refrigerant work requires a state-licensed technician for safety.
Yes — furnace and AC replacements require a mechanical permit in Detroit, even like-for-like swaps. Fees typically run $100–$300; your contractor normally pulls the permit.
Adding or altering ductwork is mechanical work that typically requires a permit in Detroit. Confirm the scope with the Buildings, Safety Engineering, and Environmental Department before starting.