Permit Required? Required
Typical Fee Range $125–$300 A mechanical permit is required for replacements; fees are based on the number of units.
Fee Method Flat rate
Apply Online Apply at Seattle Department of Construction and Inspections →

What's Required in Seattle

  • A mechanical permit is required for replacing any heating or cooling unit
  • Must follow current Washington State energy codes for system efficiency (SEER2/HSPF2)
  • Proper secondary drain pan and safety float switches required for attic installs
  • Manual J load calculations required for new system sizing to ensure proper capacity
  • Condenser units must be anchored and meet property line setbacks (typically 5 feet)
  • Must be performed by a licensed Mechanical contractor or qualified owner-occupant

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

Yes. Seattle 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 $125–$300, and the permit is issued by the Seattle Department of Construction and Inspections. 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 Seattle Department of Construction and Inspections before work starts; it's a five-minute call.

How to Get a HVAC Permit in Seattle

1

Step 1: Contractor Check

Verify the HVAC contractor is licensed and registered with SDCI.

2

Step 2: Portal Application

Submit a 'Mechanical' permit application via the Seattle Services Portal.

3

Step 3: Detail Equipment

Enter the model number and BTU rating of the new unit in the application.

4

Step 4: Fee Payment

Pay the flat permit fee ($125 minimum typical) online.

5

Step 5: Inspection

Schedule a final mechanical inspection via the portal once installation is complete.

Frequently Asked Questions

Yes, a mechanical permit is mandatory for any HVAC replacement.
Standard residential replacement permits typically range from $125 to $300.
Yes, as an owner-occupant, but you must still pull a permit and pass inspection.
Adding or altering ductwork is mechanical work that typically requires a permit in Seattle. Confirm the scope with the Seattle Department of Construction and Inspections before starting.