Plumbing Permit in King County, Washington

How to apply in King County

You apply for a residential plumbing permit at your local building department by filing an application that describes the scope of work and site, along with construction documents, before any regulated plumbing installation, alteration, or repair begins. Minor repairs that do not touch piping or fixtures are generally exempt, and once issued the permit only stays valid if work is started within its time limit.

What most plumbing permit applications include:

• A permit is required before any owner or authorized agent constructs, alters, repairs, removes, converts, or replaces a plumbing system regulated by the code (IRC R105.1).
• The application must identify and describe the work, describe the site, state the intended use and occupancy, and be signed by the applicant or an authorized agent (IRC R105.3).
• Two or more sets of construction documents must accompany the application, drawn with enough clarity to show the location, nature, and extent of the proposed plumbing work and how it will conform to code (IRC R106.1, R106.1.1).
• Minor plumbing repairs, such as clearing a stoppage or removing and resetting a water closet without rearranging pipes or fixtures, are exempt from permit (IRC R105.2).
• Once issued, a permit is only valid for a limited window, commonly 180 days, and becomes invalid if the work is not started or is abandoned within that time, though extensions can be requested (IRC R105.3.2, R105.5).

General submittal guidance from 2021 International Residential Code (IRC), Chapter 1 Scope and Administration, Sections R105 Permits and R106 Construction Documents. Source. Public Health Seattle and King County sets the exact checklist for King County.

Where to apply in King County:

• Official permit page
• Online permit portal (apply, upload plans, check status)

Inspections and closing out your permit

Plumbing inspections are timed to whatever is about to hide the pipe: underground and under-slab piping is checked before concrete covers it, rough-in piping is pressure or water tested before walls close up, and a final inspection checks every fixture and backflow protection once the work is complete.

1. Piping and equipment placed under a slab or floor must be in place and inspected before any concrete is poured or floor sheathing is installed over it (IRC R109.1.1.1).
2. Rough plumbing, along with the mechanical, gas, and electrical rough-in, must be inspected prior to covering or concealment and before fixtures or appliances are set (IRC R109.1.2).
3. Rough drain, waste, and vent (DWV) piping is tested with water, air, or (for plastic piping) a vacuum, and must show no evidence of leakage before it is closed in (IRC P2503.5.1).
4. The water-distribution piping is tested and must hold tight under the system's working pressure, or under a 50 psi air test for non-plastic piping, before it is concealed (IRC P2503.7).
5. The framing inspection cannot proceed until the plumbing rough inspection, along with the mechanical and electrical rough inspections, has been approved (IRC R109.1.4).
6. At the final drainage test, each fixture is filled and then drained, and its traps and fixture connections must prove watertight by visual inspection (IRC P2503.5.2).
7. Final inspection is made after all work required by the permit is complete, and includes confirming backflow protection, such as vacuum breakers on hose bibbs, is installed (IRC R109.1.6, P2902.4.3).

Schedule each inspection in advance and pass the final before you use the work or close the permit. Request inspections through the King County permit portal or by phone at (206) 263-9566.

Inspection sequence from 2021 International Residential Code (IRC), Section R109 Inspections and Section P2503 Inspection and Tests. Source. An open permit left un-inspected can surface later in a title search or home sale.