King County is the most populous county in Washington and the thirteenth most populous in the country. Its Permitting Division covers only the unincorporated areas — the rural east, the foothills and the pockets between cities — and on those parcels the permit is split across several agencies.
The Permitting Division provides land use, building, mechanical, fire regulatory and operating permits, code enforcement and a limited number of business licences in unincorporated King County, with most applications filed through the regional online portal.
This guide covers unincorporated King County only. Seattle, Bellevue, Kent, Renton, Federal Way, Auburn, Kirkland, Sammamish, Redmond, Shoreline, Burien and Bothell are incorporated and permit separately — 12 of the cities in this series sit inside this county.
One house, three permitting agencies. Building, land use, mechanical and fire permits come from King County Permitting. Plumbing comes from Seattle–King County Public Health, along with septic, wells and public pools. Electrical comes from the state Labor and Industries programme. Three separate applications, three separate inspection queues, and no single counter that can tell you the status of all of them.
What requires a building permit in King County?
Washington has a mandatory statewide building code. The codes enumerated in chapter 19.27 RCW, the State Building Code Act, are adopted and amended by the State Building Code Council within the Department of Enterprise Services, and they are required in all cities and counties — local government administers and enforces them rather than deciding whether to have them. A city or county may make the state code stricter but cannot opt out of it, and local changes affecting houses or apartments need State Building Code Council approval. So the question in King County is not whether a code applies, but which edition is in force and what King County Permitting has added to it.
Permit required
- New buildings, additions, alterations and change of occupancy or use
- Structural alterations, load-bearing changes, foundations, decks and retaining walls
- Plumbing work under the Uniform Plumbing Code as adopted by the state
- Mechanical and HVAC change-outs, fuel gas work and ventilation
- Work affecting the Washington State Energy Code envelope or systems
- Re-roofing above the exempt scope, demolition, and work in critical areas
Often exempt
- Ordinary repairs and maintenance replacing materials in kind
- Small accessory structures below the code threshold, where zoning allows
- Painting, flooring, cabinetry and other finish work
- Like-for-like fixture swaps with no alteration to piping
Local amendments, fee schedules and exempt thresholds differ from one jurisdiction to the next, so an exempt list from a neighbouring city is not reliable. An exemption from a building permit is never an exemption from zoning, critical areas review, the energy code or a trade permit. Confirm scope with King County Permitting before work starts.
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Rural sites carry a physical step most applicants have never met: most rural and some urban lots need a Critical Areas Designation, and during it you must flag the site — placing flags or tape at key points so county staff can identify the property boundaries and where you intend to build — with the county publishing separate instructions for how the flagging must be done
Washington has a mandatory statewide building code under chapter 19.27 RCW that every city and county enforces and may make stricter; electrical permits come from the Department of Labor and Industries unless the city runs its own programme or Tacoma Power serves the site. Building codes in Washington
Who handles permitting in King County?
The Permitting Division issues land use, building, mechanical, fire regulatory and operating permits for unincorporated King County, alongside code enforcement and some business licensing, and publishes turnaround times for residential new construction and for additions and alterations.
| Detail | Information |
|---|---|
| Department | King County Department of Local Services, Permitting Division |
| Address | 919 SW Grady Way, Suite 300, Renton, WA 98057 |
| Phone | (206) 296-6600 (9 to 11 a.m. and 12:30 to 2:30 p.m., Monday, Tuesday, Thursday and Friday); PermitQuestions@kingcounty.gov |
| Hours | In person: Monday, Tuesday and Thursday 8:30 a.m. to 3:30 p.m.; Wednesday 9:30 a.m. to 3:30 p.m.; closed Friday |
| Plumbing, septic, wells | Seattle-King County Public Health, separately |
| Electrical | Washington State Department of Labor and Industries |
| Critical areas ordinance | Updated ordinance adopted December 2025, effective February 2026 |
| Applications | Most building and land use permits through the regional online portal |
The critical areas rules were rewritten recently and the change is dated. The King County Council adopted an updated Critical Areas Ordinance in December 2025, and those regulations — excluding ones applying to critical areas inside shoreline jurisdiction — took effect in February 2026. The update expands buffers around certain critical areas in unincorporated King County and clarifies identification and analysis requirements, with the division publishing supporting bulletins through the year.
Infrastructure is rarely the county’s. Fire, water and sewer services in unincorporated areas are usually provided by special districts, and a certificate of availability from the service provider is needed to show whether water or sewer is actually available — being inside a district does not mean the connection exists. Where no service is available, on-site sewage and water well permits must be obtained before applying for the building permit.
In 2025, building permits issued in unincorporated King County authorized 7 new privately owned housing units, 5 of them single-family homes, according to the U.S. Census Bureau Building Permits Survey.
Permit types
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Get a free quote →Residential permits
Most properties in unincorporated King County can support an accessory dwelling unit, with only one allowed per primary detached dwelling or townhouse unit and either the accessory unit or the primary dwelling required to be owner-occupied. Before permitting begins an applicant must file a notice on title and affidavit with the county records office.
How Washington contractor credentials work
A general registration does not let anyone touch the wiring or the pipes. A general contractor needs a licensed electrical contractor and a licensed plumbing contractor for that work, or must hold those licences itself, and each electrical contractor must name a master electrician or a certified administrator. Owners may do their own electrical and plumbing work on their own property, with limits for buildings meant for sale or rent. Verify the registration is active and the bond and insurance current with King County Permitting and with the department, because registration lapses are common and an expired registration invalidates the credential the permit relies on.
Commercial permits
Development on rural land may involve transferable development rights: before receiving a building permit or recording a final plat or short plat, a certificate for the rights being applied must be delivered to the Permitting Division in the applicant’s name, with an extinguishment document following issuance to show the rights have been used and cannot be used again elsewhere.
Registrations, trade certifications and design professionals
Three credential layers appear on Washington projects: the state contractor registration under chapter 18.27 RCW, which nearly everyone doing the work needs; separate state trade certification for electricians and plumbers, each examined and administered by its own programme; and, on commercial and larger residential work, drawings stamped by a Washington-licensed architect or professional engineer. Confirm what King County Permitting requires for the specific building before filing.
Most Washington contractors register with the Department of Labor and Industries (with a surety bond and insurance) rather than holding a licence; electrical and plumbing contractors also need an L&I contractor licence. Contractor licensing in Washington
King County permit costs and fees
King County publishes turnaround times for residential new construction, additions and alterations alongside its fee schedule. Budget separately for the Public Health plumbing, septic and well permits and for the state electrical permit, since neither is charged by the county.
Washington sets the code statewide but leaves the fee schedule local, so two jurisdictions on the same edition can price the same project very differently. The electrical fee is the one that most often surprises people, because it is paid to L&I rather than with the building permit. Ask King County Permitting for the schedule in force on your filing date, and confirm the electrical route separately.
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Call 1-855-478-4290 →Need a real number for a specific King County project? Send us the scope, address and valuation and we will identify the edition in force, the local amendments, the electrical route and the fee categories that will apply.
Fees are set locally, plus a small state permit fee (RCW 19.27.085); the electrical fee goes to whichever body issues the electrical permit. Permit fees in Washington
Trade permits and who may pull them
Permit required
- Service installations, panel upgrades, new circuits, solar PV and EV chargers
- New plumbing, repipes, water heater change-outs, fixtures and backflow, plus gas piping (usually on a mechanical or gas permit)
- HVAC installation and change-out, ductwork, venting and commercial kitchen exhaust
- Sprinkler, standpipe and fire alarm work on commercial and multi-family structures
Typically exempt
- Replacing a fixture, switch, receptacle or light with no alteration to wiring or piping
- Clearing a stoppage without replacing or rearranging concealed piping
- Filter, thermostat and routine component service
- Like-for-like appliance repair that does not alter the connection
Plumbing and mechanical permits are local; electrical permits come from the Department of Labor and Industries unless the city runs its own electrical programme or Tacoma Power serves the site. Trade permits in Washington
How to apply for a King County building permit
12 of the cities in this series sit inside King County, and each permits its own limits.
County for building and land use, Public Health for plumbing and septic, the state for electrical.
The updated ordinance expanded buffers around certain critical areas with effect from February 2026.
Critical Areas Designation on rural and some urban lots requires physically flagging boundaries and the build location.
Being inside a water or sewer district does not mean service is available at the parcel.
Where no service is available these must be obtained before the building permit application.
Rather not deal with the King County building department?
Get a free quote →Review, corrections and what actually causes delay
In Washington the first cause of delay is the energy code, because the state code is its own instrument and more demanding than the international one most designers default to. After that comes critical areas review, which reaches ordinary residential work near wetlands, streams, steep slopes and shorelines and adds its own study and mitigation timeline. Then the electrical split, where a project waits on a local inspection that was never going to happen because the electrical permit sits with L&I. Then edition confusion around the switch-over date, when a new state edition takes effect and local amendments change with it. Build review time into the schedule and confirm the checklist with King County Permitting before filing.
The state code sets a 180-day default for permit validity, but King County may change it, so confirm the expiry on phased or delayed work. Permit validity in Washington
Inspections in King County
Where a permit is required, standard checkpoints include footing and foundation, framing, rough-in plumbing and mechanical, insulation and energy code compliance, fire systems on commercial work, and final, with a certificate of occupancy before the building is used. Inspection scheduling is split the same way as permitting: building, fire and land use through the county, electrical through the state programme, and septic, plumbing, wells and public pools through Public Health.
The point to plan around is that the electrical inspections may be booked with a different body entirely. Because L&I holds the electrical permit here, its inspector attends on the state’s schedule and the local inspector will not sign off electrical work. Sequencing a cover-up around two independent inspection queues is the practical skill on a Washington job.
Do not cover work before the required inspection has been approved. Keep the issued permits — plural — the approved plans and the energy code documentation available on site.
King County permit search and official resources
Permit records in Washington are split the same way the permits are. Where King County Permitting is the authority for unincorporated King County, it holds the building and mechanical records — plumbing and gas-piping permits come from Public Health – Seattle & King County, and while electrical permits come from the state Department of Labor and Industries (L&I). If you are buying, refinancing or renovating, check both, because a clean local record does not mean the electrical work was ever permitted.
Want this handled start to finish?
Get a free quote →Confirm the edition, the local amendments and the electrical route. Washington sets a mandatory statewide minimum under chapter 19.27 RCW, the edition changes on a three-year cycle, and every jurisdiction may make it stricter. All three questions have to be answered for the parcel and the filing date.
These are the primary sources behind this guide. Codes, fee schedules and procedures change — confirm the position for your filing date.
- King County permits
- King County critical areas overview and related permits
- King County permit guide frequently asked questions
- Labor and Industries contractor laws and rules
- Chapter 19.27 RCW, the State Building Code Act
Frequently asked questions
Who issues my plumbing permit in unincorporated King County?
Not the county. Plumbing permits, along with septic, wells and public pools, come from Seattle-King County Public Health, while building, land use, mechanical and fire permits come from King County Permitting and electrical comes from the state programme.
What is site flagging?
A physical marking step in the Critical Areas Designation process. Most rural and some urban lots need a designation, and during it you must place flags or tape at key spots on the property so county staff can identify the boundaries and where you plan to build. The county publishes separate instructions on how to do it.
Have the critical areas rules changed?
Yes, recently. The county council adopted an updated Critical Areas Ordinance in December 2025, effective February 2026 for regulations outside shoreline jurisdiction, expanding buffers around certain critical areas and clarifying identification and analysis requirements.
Inspections are where schedules slip.
Get a free quote →Which code edition applies?
The state edition as amended by the county. Washington has a mandatory statewide building code. The codes enumerated in chapter 19.27 RCW, the State Building Code Act, are adopted and amended by the State Building Code Council within the Department of Enterprise Services and are required in all cities and counties, so local government administers and enforces them rather than choosing whether to have them. The 2021 editions took effect on the fifteenth of March, 2024 after two delays, and the 2024 editions are dated to take effect on the third of May, 2027. The state adopts a new edition every three years and reviews the codes in two groups, but all of them take effect on the same date (the 2021 codes on 15 March 2024, the 2024 codes on 3 May 2027). A city or county may make the state code stricter but cannot opt out of it; local changes affecting houses or apartments need State Building Code Council approval, and the residential energy code cannot be changed locally.
Do I have water and sewer?
Not necessarily, even inside a district. Fire, water and sewer in unincorporated areas are usually provided by special districts, and you need a certificate of availability from the provider. Where no service is available, on-site sewage and water well permits must be obtained before applying for the building permit.
Who registers my contractor?
The state. Most Washington contractors register rather than hold a licence; electrical and plumbing contractors must also hold an L&I contractor licence. Under chapter 18.27 RCW a contractor registers with the Department of Labor and Industries, files a continuous surety bond of $30,000 as a general contractor or $15,000 as a specialty contractor, and keeps liability insurance on file, renewing every two years. Registration is not a competence test and does not authorise trade work: electrical certification comes under chapter 19.28 RCW and plumbing under chapter 18.106 RCW. The electrical permit comes from the state, because the Electrical Program at the Department of Labor and Industries (L&I) issues electrical permits and carries out electrical inspections here under chapter 296-46B WAC.
Simplify King County permitting with Alliance Permitting
Three agencies, three queues and a site that has to be physically flagged. Sequencing that is the entire job on a rural King County parcel.
Trusted by leading builders, developers, and national contractors — 21+ years of filing in the jurisdictions we write about.
Contractors and builders choose Alliance for King County because the work is done by people who have stood at the counter:
- 21+ years of filing, so the edition and the electrical route are settled before submission
- We confirm which state code group governs each part of the work on your filing date
- State contractor registration, bond and insurance verified as active before filing
- Energy code and critical areas documentation prepared rather than discovered in review
- Two inspection queues sequenced so a cover-up never waits on the wrong inspector
Alliance Permitting is a permit documentation and submission company in Washington. We prepare your paperwork, file it correctly and coordinate with the permitting authority through issuance. We are not a contractor and we do not perform licensed plan review or inspections; that work stays with your licensed team and the jurisdiction.
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More Washington permitting guides
This guide is provided by Alliance Permitting for general information about King County permitting. Requirements, fees, and procedures change; confirm details with the permitting authority before relying on them.