HVAC Permits in Pierce, King and Thurston Counties: What Homeowners Should Know

Short answer: if you're replacing a furnace, heat pump, air conditioner, or ductwork in Pierce, King, or Thurston County, the work almost certainly requires a mechanical permit — and if you've hired a reputable contractor, you shouldn't have to think about it, because they pull it for you. Here's how the system works in the South Sound and why the permit is genuinely on your side.

Why do mechanical permits exist at all?

A permit triggers an independent inspection of gas connections, venting, electrical work, refrigerant piping, and clearances by someone with no financial stake in the job. That's the entire value: a second set of trained eyes verifying that the equipment heating your home and venting combustion gases was installed to code. Permits also create a public record that the work was done and inspected — which matters enormously later, as we'll get to.

Who issues the permit for my address?

It depends on whether your home sits inside city limits or in unincorporated county territory:

• Inside city limits — cities like Lakewood, Tacoma, Puyallup, Olympia, and Federal Way run their own permit centers, and mechanical permits for addresses within those limits go through the city.
• Unincorporated county addresses — communities like Graham, Spanaway, Frederickson, and other areas outside any city boundary permit through their county's planning and development department instead.
• Electrical work — in much of Washington, the electrical portion of an HVAC job (a new circuit for a heat pump, for example) is permitted separately through the Washington State Department of Labor & Industries, though some cities administer their own electrical programs.

If that sounds like a maze — the same job can involve different offices depending on which side of a city line you live on — you've spotted exactly why this is contractor work, not homeowner homework.

Who is responsible for pulling the permit?

Your contractor. A licensed contractor pulling permits under their own license and insurance is the industry norm, and it's how it should be. Be wary of any contractor who suggests skipping the permit to "save time," or worse, asks you to pull an owner's permit for work they're performing — that shifts liability for their work onto you. Ares Comfort Systems (WA LIC # ARESCCS766CA) handles the full permit lifecycle on every job: application, fees, scheduling the inspection, and being there to close it out.

What happens if work was done without a permit?

Nothing — until you sell the house. Unpermitted mechanical work is a classic home-sale landmine:

• Disclosure. Washington sellers complete a disclosure form, and known unpermitted work generally has to be disclosed.
• Inspection flags. Buyers' inspectors routinely spot recent equipment with no permit on record, and buyers' agents know how to check.
• Deal friction. The fix at that point — retroactive permits, inspections of concealed work, possible corrections — happens on the buyer's timeline, with your sale hanging on it. It's always more expensive and stressful than simply permitting the work when it was done.

There's also an insurance angle worth knowing: if unpermitted equipment is ever implicated in a loss, you'd rather not be arguing with an adjuster about it.

What does the final inspection look like?

After installation, the jurisdiction sends an inspector to verify the work: clearances, venting, gas and electrical connections, condensate handling, seismic strapping where required. It's typically a brief visit, your contractor coordinates the scheduling, and passing it closes the permit — completing the public record that protects you at resale. Keep the paperwork with your house documents.

The bottom line

A permit isn't red tape working against you — it's independent verification working for you, and the record it creates is part of your home's value. When you book with Ares Comfort Systems, the permit process is built into the job from the first visit. Schedule a consultation and we'll handle the paperwork side of your project from application through final inspection.