Do you need a permit for an AC unit, heat pump, or generator in Seattle, WA?
It depends on the details of your project.
Replacing a furnace needs a permit.
Every split-system heat pump or AC needs a refrigeration permit.
A standby generator needs an electrical permit for its transfer switch.
A person last checked these rules on October 19, 2026. This is guidance only, so confirm with Seattle before you build.
Check your exact lot
Your zoning district sets the setbacks, and a flood zone can change the permit answer. Enter your address to see both.
Permits a AC unit, heat pump, or generator can need in Seattle
| Permit | When it applies |
|---|---|
| Furnace or refrigeration permit | Seattle requires a permit for any furnace replacement and for any heat pump or AC with refrigerant piping. |
| Electrical permit | A standby generator needs an electrical permit for its transfer switch. A new outdoor unit needs a new circuit and disconnect.Medium confidence |
| Gas piping permit | A gas or propane line to the equipment needs a fuel-gas permit.Medium confidence |
Local details
- Call 811 at least a few days before you dig footings or post holes. Utility locating is free.
- HOA covenants and deed restrictions can be stricter than city rules. Check yours before you build.
How to apply
- Seattle Services Portal
- SDCI common projects
- SMC 23.44, Neighborhood Residential
- Phone: (206) 684-8600
Common questions
- When does an AC unit, heat pump, or generator need a mechanical permit in Seattle?
- Seattle requires a permit for any furnace replacement and for any heat pump or AC with refrigerant piping. Generators are covered by the electrical permit.
- Where do I apply for an AC unit, heat pump, or generator permit in Seattle?
- Apply through Seattle Services Portal, or call (206) 684-8600.
Sources
- Seattle SDCI, Furnace & Refrigeration Permits & Inspections. Checked 2026-10-22
You need a permit for any furnace replacement or alteration... You need a refrigeration permit for any split system heat pump, air conditioner, or any job that requires refrigeration piping.
- Seattle SDCI, Electrical Permit. Checked 2026-10-22
You need an electrical permit any time electrical wiring is installed, altered, extended, or connected to any electrical equipment... Small solar PV systems – If your solar PV system is rated under 7.7KW, you can apply online without plan review.
- 2024 IRC R105.2, Work exempt from permit (text published by the City of Benson, AZ). Checked 2026-10-19
One-story detached accessory structures, provided that the floor area does not exceed 200 square feet. Fences not over 7 feet high. Decks not exceeding 200 square feet in area, that are not more than 30 inches above grade at any point, are not attached to a…