Issaquah, WA Building Safety: Plumbing Permits (2026)

IMC 16.04.080 adopts the 2021 Edition of the Uniform Plumbing Code as adopted by the State Building Code Council in Chapter 51-56 WAC. Issaquah excludes Chapter 1, "Administration," Chapter 12, "Fuel Gas Piping," and Chapter 14, "Firestop Protection." It adds four appendix chapters: A on sizing the water supply system, B on combination waste and vent systems, I on PEX tubing for hot- and cold-water distribution, and M, the Peak Water Demand Calculator. Two further carve-outs matter to contractors. The UPC requirements on venting and combustion air of fuel fired appliances in UPC Chapter 5 are not adopted, and neither are the UPC portions addressing building sewers. Fats, oils, and grease are regulated under Chapter 16.38 IMC instead. Where Appendix I conflicts with the manufacturer's installation instructions, the conditions of the listing and the manufacturer's instructions apply.

The permit process comes from the Construction Administrative Code adopted at IMC 16.04.010. Section 105.1 requires an owner or authorized agent who intends to erect, install, enlarge, alter, repair, remove, convert or replace any gas, mechanical or plumbing system to apply to the Building Official and obtain the required permit first. Section 105.1.1 lets the Building Official issue an annual permit, instead of a permit for each alteration to an already approved plumbing installation, to a person, firm or corporation regularly employing one or more qualified trade persons on premises it owns or operates. The holder must keep a detailed record of the alterations. The exempt-work list covers stopping or repairing leaks in drains, water, soil, waste or vent pipes and clearing stoppages, but if a trap or pipe is defective and must be removed and replaced with new material, that is new work requiring a permit and inspection. Under Section 107.2.10, plans must be submitted whenever the scope of plumbing work is too complex for inspection alone, as the Building Official determines.

A plumbing permit expires at the same time as the associated building permit. If no building permit is issued, it expires 1 year from the date of issuance.