HVAC permit requirements across 16 Seattle-area cities
Side-by-side: which of Seattle, Bellevue, Kirkland, Redmond, Sammamish, Issaquah, Renton, Kent, Federal Way, Mercer Island, Shoreline, Tacoma, Lakewood, Puyallup, Everett, Lynnwood require a permit for an HVAC, and what triggers one — each row quoted from the city's own code or permit page, with the source linked. Fees and review times appear where the city publishes them.
12 of 16 cities have authoritative rules on file · 3 always require a permit · 13 depend on the scope · 0 do not.
King County
| Jurisdiction | Permit? | Threshold | Fee | Review days | Source |
|---|---|---|---|---|---|
city | Depends on scope | Installing or replacing heating, cooling or ventilation equipment needs a mechanical permit; portable appliances, minor part replacements and small self-contained units (10 lb of refrigerant or less, 1 hp or less) do not. A permit is required for installing, moving, or replacing a furnace and/or heat pump (and an air conditioner also needs an electrical permit). | — | — | Cite verified 2026-05-29 |
city | Depends on scope | Installing or replacing heating, cooling or ventilation equipment needs a mechanical permit; a portable unit or a minor part replacement does not. WAC 51-52 (2021 IMC) and WAC 51-56 (2021 UPC) require mechanical permit for any equipment install, replacement, or relocation. WSEC R403 requires sizing per Manual J/S/D for new equipment. | — | — | Cite verified 2026-10-02 |
city | Depends on scope | Installing or replacing heating, cooling or ventilation equipment, gas appliances or gas piping needs a mechanical permit; portable appliances, work on the piping inside the equipment, minor part replacements and small self-contained refrigeration units do not, except outdoors in a flood hazard or critical area. A mechanical permit is required for furnaces, AC, heat pumps, gas appliances and gas piping. Mechanical work tied to a building permit is a component of it; standalone fixtures issue online. For one- and two-family dwellings the fee is 8% of the determined building permit fee for NEW CONSTRUCTION only. For remodels, additions and anything other than new construction it is a flat $62.88 per new appliance, per duct system, or for gas piping alone, with a $62.88 minimum and a $422.04 maximum; a like-for-like water heater or furnace replacement is $62.88. A separate technology fee applies. Commercial and multifamily are charged on valuation instead (Table C-2). | — | — | Cite verified 2026-05-29 |
city | Depends on scope | Installing or replacing heating, cooling or ventilation equipment needs a mechanical permit; a portable unit or a minor part replacement does not. A mechanical permit is required for heating/cooling systems, HVAC, gas pipes, gas water-heater replacements, and other mechanical systems; portable appliances are exempt. Typically processed within 2–3 business days. | — | 2–3 days | Cite verified 2026-05-29 |
city | Depends on scope | New or replaced heating, cooling or ventilation equipment and gas piping need a mechanical permit; portable appliances, part replacements that do not alter the equipment's approval, and small self-contained refrigeration units (10 lb of refrigerant or less, motor 1 hp or less) do not, except in a flood hazard area, a critical area or its buffer, or a wildland-urban interface (WUI) location. A mechanical permit is required for new/replaced mechanical equipment and gas piping. Fuel-gas piping and new fuel-gas fixtures require a Mechanical Permit (not a plumbing permit). | — | — | Cite verified 2026-10-18 |
city | Depends on scope | Installing or replacing heating, cooling or ventilation equipment needs a mechanical permit; portable appliances, minor part replacements and a self-contained unit with 10 lb of refrigerant or less and a motor of 1 hp or less do not, except outside the house's envelope in a flood hazard or critical area. WAC 51-52 (2021 IMC) and WAC 51-56 (2021 UPC) require mechanical permit for any equipment install, replacement, or relocation. WSEC R403 requires sizing per Manual J/S/D for new equipment. | — | — | Cite verified 2026-04-29 |
city | Depends on scope | Installing or replacing heating, cooling or ventilation equipment needs a mechanical permit; portable appliances, work on the piping inside the equipment, minor part replacements and self-contained refrigeration systems with 10 lb of refrigerant or less or a motor of 1 hp or less do not. Mechanical systems require a separate trade permit; all trade permits are separate and not included in the building permit. | — | — | Cite verified 2026-05-29 |
city | Depends on scope | Installing or replacing a furnace, heat pump, air conditioner, ducts or gas piping needs a mechanical permit. Portable appliances need none; replacing a minor part, or a small self-contained unit (10 lb of refrigerant or less, motor 1 hp or less), needs none except in a flood hazard area or a critical area. A mechanical permit is required for fixed systems (furnace, heat pump, A/C, ducts, gas piping); portable heating/cooking/clothes-drying appliances are exempt. Emergency replacement requires an application the next business day. | — | — | Cite verified 2026-05-29 |
city | Depends on scope | Installing or replacing heating, cooling or ventilation equipment needs a mechanical permit; portable appliances, part replacements and small self-contained refrigeration units (10 lb of refrigerant or less, 1 hp or less) do not. WAC 51-52 (2021 IMC) and WAC 51-56 (2021 UPC) require mechanical permit for any equipment install, replacement, or relocation. WSEC R403 requires sizing per Manual J/S/D for new equipment. | — | — | Cite verified 2026-10-02 |
city | Depends on scope | Installing or replacing heating, cooling or ventilation equipment needs an SDCI mechanical permit. Replacing a component part does not, and neither do portable units that together cover 40 percent or less of the home's requirement and total 3 kW (electric) or 10,000 Btu input (fuel) or less. In a special flood hazard area, or on a parcel with an environmentally critical area, replacing a component part still needs floodplain development approval or the Director's approval of an exemption. SDCI requires Mechanical Permit for any equipment install or replacement. WSEC R403 requires Manual J/S/D sizing on new systems. | — | — | Cite verified 2026-04-26 |
city | Always | Adding or replacing a furnace, heater, AC, heat pump, ductwork or exhaust fan needs a mechanical permit. A mechanical permit is required for adding or replacing a furnace, heaters, air conditioners, appliance vents, boilers, heat pumps, air handlers, duct work, ventilation fans, and exhaust hoods/ducts. Simple permits process in same-day to 3 business days. | Mechanical permit + electrical permit (if new circuit) + plumbing permit (if condensate to drain). Shoreline's Construction Fees handout (12/2025): a residential mechanical and plumbing permit is $267.00 up to 4 fixtures, plus $12.00 per fixture over 4. Each mechanical or plumbing permit submitted separately is assessed its own $267.00 base. | 0–3 days | Cite verified 2026-05-17 |
Pierce County
| Jurisdiction | Permit? | Threshold | Fee | Review days | Source |
|---|---|---|---|---|---|
city | Always | Any equipment install, replacement or relocation needs a mechanical permit. WAC 51-52 (2021 IMC) and WAC 51-56 (2021 UPC) require mechanical permit for any equipment install, replacement, or relocation. WSEC R403 requires sizing per Manual J/S/D for new equipment. | — | — | Cite verified 2026-04-29 |
city | Always | Any equipment install, replacement or relocation needs a mechanical permit. WAC 51-52 (2021 IMC) and WAC 51-56 (2021 UPC) require mechanical permit for any equipment install, replacement, or relocation. WSEC R403 requires sizing per Manual J/S/D for new equipment. | — | — | Cite verified 2026-04-29 |
city | Depends on scope | Portable appliances and minor part replacements are exempt; anything fixed needs a mechanical permit. Exempt: portable heating/ventilation/cooling appliances; portable evaporative coolers; steam/hot/chilled-water piping within heating/cooling equipment regulated by code; minor part replacements that don't alter equipment approval; self-contained refrigeration systems with ≤10 lb refrigerant or ≤1 hp motors; portable-fuel-cell appliances not connected to fixed piping or power grid. | — | — | Cite verified 2026-04-29 |
Snohomish County
| Jurisdiction | Permit? | Threshold | Fee | Review days | Source |
|---|---|---|---|---|---|
city | Depends on scope | Installing or replacing heating, cooling or ventilation equipment needs a mechanical permit; a portable unit or a minor part replacement does not. WAC 51-52 (2021 IMC) and WAC 51-56 (2021 UPC) require mechanical permit for any equipment install, replacement, or relocation. WSEC R403 requires sizing per Manual J/S/D for new equipment. | — | — | Cite verified 2026-10-02 |
city | Depends on scope | Installing or replacing heating, cooling or ventilation equipment needs a mechanical permit; a portable unit or a minor part replacement does not. WAC 51-52 (2021 IMC) and WAC 51-56 (2021 UPC) require mechanical permit for any equipment install, replacement, or relocation. WSEC R403 requires sizing per Manual J/S/D for new equipment. | — | — | Cite verified 2026-10-02 |
How this table is built
Each row reflects the most-recently-verified authoritative rule on file for that jurisdiction and project type. “Pending verification” means we have the jurisdiction in our database but haven't yet personally checked the city page for HVAC rules — those rows fall back to county or WA-state baselines until verified. Sources link directly to the city or county page we read on the verified-on date. See our data-quality leaderboard for how we keep these current.