The single most useful thing a Seattle homeowner can know about permits is which body issues them, because the wrong assumption sends you looking in the wrong place and building the wrong timeline into your project.
SDCI, not King County
The Seattle Department of Construction and Inspections handles permitting and inspection within Seattle city limits. King County Permitting handles unincorporated King County — areas not inside any city. Everywhere else in the county, the relevant city department applies.
This matters more than it sounds. It means a contractor experienced in Bellevue is not thereby experienced in Seattle’s process, and it means guidance you find about King County permitting may not describe what you will actually encounter.
What generally needs a permit
Structural work. Changes to the building envelope. Plumbing relocation. Most electrical work. Additions and conversions. Substantial roofing work. Decks above a certain height. Anything altering the footprint or the use of a space.
What generally does not: cosmetic work, like-for-like fixture replacement, painting, flooring, and minor repairs. The line is real but it sits in specific places, and the specifics change over time — which is why confirming for your particular project is better than relying on a general list.
Timeline is a project variable
Treat permitting as part of the schedule rather than an administrative step happening in parallel. Review takes time, and complex or unusual projects take longer. Inspections have to be scheduled, and work often cannot proceed past a stage until the relevant inspection has passed.
Ask your contractor for a schedule that shows permit and inspection points explicitly. A programme that runs straight from demolition to completion without acknowledging them is not a real programme.
Seattle-specific considerations
Some Seattle neighbourhoods and structures carry additional review requirements affecting what may be built or altered. Certain areas have design review; some structures have historic considerations; specific geographic conditions such as steep slopes carry their own requirements.
None of this makes a project impossible, but all of it affects timeline and sometimes scope. It is worth establishing early whether anything additional applies to your property, because discovering it after design work is complete is expensive.
Older housing and code
Seattle’s substantial stock of older homes means permitted work frequently surfaces existing conditions that do not meet current code. Opening a wall can reveal knob-and-tube wiring, undersized service or non-compliant framing.
Bringing the work area up to current standards is generally part of doing the job properly, and it is one reason Seattle remodels benefit from a genuine contingency in the budget. It is not a contractor inventing work — it is what happens when old buildings meet current requirements.
Getting it right
Have your contractor confirm what is required for your specific project and address, in writing. Have them pull the permits. Build review and inspection time into the schedule from the start. And check the current position with SDCI directly if anything is unclear, since requirements do change.